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46: Mikrobna hrana - Biologija

46: Mikrobna hrana - Biologija



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ciljevi učenja

  • Promatrajte ulogu bakterija u fermentaciji jogurta i medovine

JOGURT

Ova fermentacija mliječnom kiselinom vjerojatno je bila način da ljudi sačuvaju mlijeko, ali ipak ubiju patogene organizme. Nizak pH inhibira većinu mikroorganizama: međutim, fermentirajući mikrobi jesu Streptococcus thermophilus i Lactobacillus vulgaricus. Dobivena tekstura nalik kremi je gruš koji nastaje kiselim nusproduktom razgradnje laktoze, nakon čega slijedi koagulacija mliječnog proteina kazeina.

MEAD

Medovina je vrlo staro fermentirano piće. Glavni sastojak svake medovine je med, ali tu su i voće i začini dodani kao arome. Koncentracija alkohola varira od 8-18%. Promjenom udjela meda i vode može se promijeniti krajnji proizvod od suhog i laganog do slatkog i teškog tijela.

Moramo natjerati kvasac da se anaerobno metabolizira --- da fermentira. Kontejneri će imati zračne brave za odsijecanje kisika i zadržavanje ugljičnog dioksida. Jedna se molekula šećera mijenja u dvije molekule alkohola i dvije molekule ugljičnog dioksida.

POTREBNI MATERIJALI

I za jogurt i za medovinu

  • ledena kupka
  • termometar
  • rešo

Za jogurt

  • 8 oz. mlijeko s niskim udjelom masti
  • Obični jogurt Dannon s aktivnim kulturama
  • žlica
  • Čaša od 1 litre
  • 2 žlice. obrano mlijeko u prahu
  • Graduirani cilindar od 500 ml
  • šalica i poklopac od stiropora

Za medovinu

  • 6 oz. med
  • ZAČINI: 1 cijeli klinčić malo ispucan, 1 kriška đumbira, 1 žličica. korica naranče, 1/2 štapića cimeta izlomljeno
  • tikvica (zapremina = 5 L)
  • staklena boca za fermentaciju medovine + zračna komora (dijeli se s razredom)
  • Čaša od 2 L
  • 1 L graduirani cilindar
  • limunska kiselina u prahu
  • sladni prah
  • vegetom
  • bentonit u prahu
  • Saccharomyces starter kvasca

POSTUPCI

Jogurt

Sljedeći recept je za 2 spremnika jogurta od 16 oz. unci ukupno.

  1. Odmjerite 1 šalicu (236 ml. = 1 šalicu) mlijeka, optimalno niskomasnog mlijeka.
  2. Dodajte 1 razinu žlica. obranog mlijeka u prahu u mlijeko (dodaje dodatni protein) i promiješajte.
  3. Stavite kuhati smjesu na srednje jaku vatru 30 sekundi uz stalno miješanje. Ne želite da mlijeko izgori na dno čaše ili tikvice. Ohladite mlijeko na oko 45 ° C pomoću termometra za provjeru temperature.
  4. Inokulum koji se koristi u razredu je trgovina mješovitom robom, obični jogurt (s aktivnim kulturama). Koristite 1 žličicu. jogurta kao početne kulture, umiješajte ga u mlijeko staklenom šipkom za miješanje.
  5. Smjesu ulijte u 1 šalicu od stiropora i pokrijte poklopcem.
  6. Inkubirajte na 37 ° C 9-15 sati ili dok ne postignete željenu čvrstoću. Osoblje laboratorija uklonit će uzorke jogurta sljedeći dan.
  7. Stavite u hladnjak dok se ne ohladi. Dodajte med ili voće kad ste spremni za jelo.

Medovina

Sljedeći recept je za 700 ml medovine.

  1. Pomiješajte 500 ml vode, klinčića, đumbira, naranče i cimeta.
  2. Pustite da kuha 10 minuta i kuhajte 5 minuta.
  3. Dodajte 6 oz. meda (sipajte malo ukuhane vode u posudu za med da se sve izbaci).
  4. Prilikom dodavanja meda u vruću ili kipuću vodu, STORNO STAVLJAJTE !! Inače, med će otići ravno na dno posude, gdje će se karamelizirati i opržiti. Tijekom kuhanja formirat će se pjena koju treba ukloniti papirnatim ručnicima. Otopinu meda vratite na vrenje nekoliko minuta.
  5. Dodajte 1/4 žličice. otopine bentonita u med: to će pomoći pri taloženju krutog materijala.
  6. Nakon što se ohladi na 45 ºC, može se dodati starter kvasca i otopina medene vode napuniti u tikvicu.
  7. Dodajte 1/4 žličice. limunske kiseline i 1/2 žličice. ekstrakt slada u otopinu (vitamini i kiselost su korisni za kvasac). Možete dodati i mrvicu Vegemita (dodaje dodatne vitamine za rast kvasca).
  8. Za smanjenje kisika, tikvica će se zatvoriti zračnom komorom. Ugljikov dioksid će se ispustiti.
  9. Medovicu napunite bocom.
  10. Obično je potrebno oko 3 tjedna za dobivanje medovine, ali vrijeme ovisi o količini kvasca i medu. Nakon fermentacije, dio medovine možete uliti u malu sterilnu bočicu (peći 1 sat na 350º F.) tako da može STARITI. Odležavanje medovine smanjit će neke 'grube' rubove i učiniti je suptilnijim vinom. Inače ćemo medovinu kušati nakon samo nekoliko tjedana kratke fermentacije.

Starter kvasca

Kvasac, Saccharomyces, izađite iz pakiranja suhi i uspavani. Ova mješavina će omogućiti suhom kvascu da se počne metabolizirati, tako da se mogu jednostavno "skinuti" kada se dodaju u otopinu meda. Starter s kvascima bit će napravljen 1 dan unaprijed i bit će vam dan tijekom laboratorija. Međutim, u slučaju da ste zainteresirani, evo recepta (ovaj predjelo će napraviti 7 1/2 galona medovine).


3 šalice vode

3 žlice šećera

1/3 soka limunovog kvasca za 7,5 litara medovine

Svi se sastojci pomiješaju u staklenoj posudi, promućkaju, boca se labavo zatvori krpom i sjedi preko noći. Sljedeći dan trebao bi biti u potpunoj fermentaciji i može se dodati vašem moštu (nefermentirana otopina svježeg meda). Svaki će stol dobiti 20 ml startera kvasca za izradu 700 ml medovine.

Resursi

Zečja noga Meadery

PITANJA

  1. Opišite kako bakterije proizvode konzistenciju jogurta --- kemijsku reakciju, korištene hranjive tvari, krajnju proizvodnju, promjene pH.
  2. Polazni materijal vina obično je žitni ili voćni sok neke vrste, za razliku od medovine, koja koristi polazni materijal _________.
  3. Zašto morate hladiti mlijeko na oko 45o C prije dodavanja starter kultura?

Proizvodnja etanola | Mikrobiologija

Trenutno se za proizvodnju etanola koristi mikrobna proizvodnja jedne od organskih sirovina iz biljnih tvari, poput melase. Ovaj alkohol proizveden je fermentacijom u ranim danima, ali dugi niz godina kemijskim putem putem katalitičke hidratacije etilena.

U moderno doba pažnja se posvećivala proizvodnji etanola za kemijske svrhe i gorivo mikrobnom fermentacijom. Etanol se danas proizvodi danima upotrebom šećerne repe, krumpira, kom, manioke i šećerne trske (slika 20.6).

Za proizvodnju etanola u industriji korišteni su i kvasci (Saccharomyces cerevisiae, S. uvarum S. carlsbergensis, Candida brassicae, C. utilis, Kluyveromyces fragilis, K. lactis) i bakterije (Zymomonas mobilis).

Komercijalna proizvodnja provodi se sa Saccha & shyromyces cerevisiae. S druge strane, uvarum se također uvelike koristio. Candida utilis koristi se za fermentaciju otpadnih sulfitnih otopina budući da fermentira i pentoze.

Nedavno je pokus s Schizosaccharomycesom pokazao obećavajuće rezultate. Kada se koristi sirutka iz mlijeka, za proizvodnju etanola preporučuje se soj K. fragilis. Također je utvrđeno da Fusarium, Bacillus i Pachysolen tannophilus (kvasac) mogu pretvoriti pentozne šećere u etanol.

Teoretski je zanimljivo napomenuti da proces fermentacije zadržava većinu energije šećera u obliku etanola. Toplina izgaranja krute saharoze iznosi 5,647 MJ mol-1, toplina izgaranja glukoze je 2,816 MJ mol -1, ali oslobađanje topline je 1,371 MJ mol-1.

Jednačine su date u nastavku:

Tako gornje reakcije pokazuju da se 97% šećera pretvara u etanol. No u praksi, fermentacijski prinos etanola iz šećera iznosi oko 46% ili će sto grama čiste glukoze dati 48,4 grama etanola, 46,6 g CO2, 3,3 grama glicerola i 1,2 g kvasca. Biosinteza etanola dana je na slici 20.6.

Važno je napomenuti da etanol u visokim koncentracijama inhibira kvasac. Stoga koncentracija etanola smanjuje brzinu rasta kvasca koja utječe na biosintezu etanola.

Može proizvesti oko 10-12 % etanola, ali mana kvasca je to što ima ograničenje pretvaranja cijele biomase izvedeno njihovom sposobnošću pretvaranja ksiluloze u etanol. Zymomonas ima prednost nad kvascem što ima osmotsku toleranciju na veću koncentraciju šećera. Relativno ima visoku toleranciju na etanol i ima specifičniju stopu rasta.

1. Priprema podloge:

Za proizvodnju etanola koriste se tri vrste podloga:

(a) supstrat koji sadrži škrob,

(b) sok od šećerne trske ili melase ili šećerne repe,

(c) otpadni proizvodi od drva ili obrađenog drveta. Proizvodnja etanola iz sirutke nije održiva.

Ako se koriste sojevi kvasca, škrob se mora hidrolizirati jer kvasac ne sadrži amilaze. Nakon hidrolize nadopunjuje se celulozama mikrobnog podrijetla radi dobivanja reducirajućih šećera. Za oko 1 tonu škroba potrebna je 1 litra amilaze i 3,5 litre glukoamilaze. U pretvaranje škroba u etanol uključeni su sljedeći koraci (slika 20.7).

S druge strane, ako se za proizvodnju etanola koristi melasa, bagasse također može dati etanol nakon fermentacije. Nekoliko drugih nekonvencionalnih izvora energije, kao što je biomasa vodenih biljaka, drvo nakon hidrolize s celulozama daje etanol. Otpadna otopina sulfita, otpad koji je ostao nakon proizvodnje papira, također sadrži heksozu kao i pentozni šećer. Prvi se mogu lako mikrobiološki pretvoriti.

Etanol se proizvodi kontinuiranom fermentacijom. Stoga se veliki fermentori koriste za kontinuiranu proizvodnju etanola. Proces se razlikuje od zemlje do zemlje. Indija, Brazil, Njemačka, Danska imaju vlastitu tehnologiju proizvodnje etanola.

Uvjeti fermentacije su gotovo slični (pH 5, temperatura 35 ° C), ali su kulture i uvjeti kulture različiti. Fermentacija se obično provodi nekoliko dana, ali u roku od 12 sati počinje proizvodnja. Nakon što fermentacija završi, stanice se odvajaju kako bi se dobila biomasa stanica kvasca koje se koriste kao jednostanični protein (SCP) za hranu za životinje.

Medij za kulturu ili supernatant obrađuje se za oporabu etanola (slika 20.6). Etanol se također proizvodi serijskom fermentacijom jer se ne nalaze značajne razlike ni u serijskoj, ni u kontinuiranoj fermentaciji.

Iako je, kako je ranije rečeno, unutar 12 sati Saccharomyces cerevisiae počinje proizvoditi etanol brzinom od 10% (v/v) sa 10-20 g stanica suhe težine/litri. Smanjenje vremena fermentacije postignuto je korištenjem kontinuiranog recikliranja stropa u fermentaciji.

Etanol se može oporabiti do 95 posto uzastopnim destilacijama. Da bi se dobilo 100 posto, potrebno je formirati azeotropnu smjesu koja sadrži 5 posto vode. Tako se nakon destilacije iz azeotropne smjese etanola, vode i benzena uklanja 5 posto vode. U ovom postupku uklanja se etanol benzen-voda, a zatim azeotropna smjesa etanol-benzen, tako da se dobije apsolutni alkohol.

Neubergova ’s fermentacija:

Kvasci tijekom fermentacije koriste piruvat što rezultira stvaranjem posrednog proizvoda acetaldehida.

To je zarobljeno vodikovim sulfitom kako bi se dobio acetaldehid u taloženom obliku, a nastanak tekućeg produkta je glicerol, kako je dolje prikazano:

Sada umjesto acetaldehida, dihidroksiaceton fosfat djeluje kao akceptor vodika koji se reducira u glicerol-3-fosfat.

Nakon uklanjanja fosfata, tj. Defosforilacije, daje glicerol kako je dolje navedeno:

Neubergov proces fermentacije kategoriziran je kao nagrada i treća fermentacija.

Prva jednadžba fermentacije data je u nastavku:

2Glukoza + H2O → C2H5OH + acetat + glicerol + 2CO2


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Mikroorganizmi & amp; sastojci dobiveni mikrobima koji se koriste u hrani (djelomični popis)

Sastojci hrane mogu biti "aditivi u hrani" koje je odobrila FDA za posebne namjene ili GRAS (općenito priznate kao sigurne) tvari. Tvar može biti GRAS samo ako se njezino opće priznanje sigurnosti temelji na stavovima stručnjaka kvalificiranih za procjenu sigurnosti tvari. Status GRAS -a može se temeljiti na povijesti sigurne uporabe hrane prije 1958. ili na znanstvenim postupcima koji zahtijevaju istu količinu i kvalitetu dokaza koji bi bili potrebni za dobivanje propisa o aditivima u hrani. Budući da status GRAS -a može potvrditi FDA ili ga neovisno odrediti kvalificirani stručnjaci, propisi FDA -e ne uključuju sve sastojke GRAS -a, a posebne upotrebe opisane u propisima GRAS -a možda nisu sveobuhvatne za navedene sastojke.

Donji popis uključuje neke sastojke koji nisu navedeni u 21 CFR -u, ali su bili predmet pisma mišljenja FDA -e pojedincima koji su pitali hoće li se FDA usprotiviti upotrebi sastojka u hrani na temelju neovisnog GRAS -a. Budući da se popis ne ažurira redovito, pitanja o regulatornom statusu mikroorganizama ili sastojaka dobivenih iz mikroba koji se ne nalaze na ovom popisu mogu nam se uputiti putem elektroničke pošte na adresu [email protected]

Sljedeći popis, koji djelomično proizlazi iz propisa FDA -e u naslovu 21. Kodeksa saveznih propisa (21 CFR), uključuje odobrene aditive za hranu, tvari čiji je status GRAS potvrđen od strane FDA -e i tvari koje je FDA navela kao GRAS na temelju povijesti sigurna upotreba u hrani. Osim toga, mikroorganizmi i sastojci dobiveni mikrobima mogu biti predmet GRAS obavijesti. Za dodatne informacije pogledajte sažeti popis sastojaka GRAS -a.

Slijedi zbirka aditiva za hranu navedenih u naslovu 21. Kodeksa saveznih propisa (21 CFR), dijelovi 172. i 173., koji potječu od mikroorganizama. Ovaj popis uključuje i izvore morskih algi. Uvjeti za njihovu uporabu propisani su u referentnim propisima i temelje se na korištenju dobre proizvodne prakse.

Za pristup dolje navedenim propisima, upišite broj naslova, koristite donje veze za pristup web stranici Državne tiskare.

Tablica 1. Dodaci hrani dobiveni od mikroorganizama navedenih u 21 CFR 172 i 173
Uredba u 21 CFR -u Sastojak
§172.155 Natamicin izveden iz Streptomyces natalensis i Streptomyces chattanoogensis
§172.325 Protein kvasca iz pekare dobiven iz Saccharomyces cerevisiae
§172.590 Ekstrakt klica od kvasca i slada, izveden iz Saccharomyces cerevisiae, Saccharomyces fragilis, Candida utilis
§172.620 Carrageenan, hidrokoloid izvađen iz sljedećih članova obitelji Gigartinaceae i Soliericeae razreda Rodophyceae (crvene morske alge): Chondrus crispus, Chondrus ocellatus, Eucheuma cottonii, Eucheuma spinosum, Gigartina acicularis, Gigartina pistillata, Gigartina radula, Gigartina stellata
§172.655 Furcelleran, rafinirani hidrokoloid izvađen iz Furcellaria fastigiata razreda Rodophyceae (crvene morske alge)
§172.695 Ksantanska guma izvedena iz Xanthomonas campestris
§172.725 Giberelična kiselina dobivena fermentacijom iz Fusarium moniliforme
§172.896 Osušeni kvasci, Saccharomyces cerevisiae, Saccharomyces fragilisi sušeni torula kvasac, Candida utilis
§172.898 Pekarski kvasac glikan iz Saccharomyces cerevisiae
§173.110 Amiloglukozidaza izvedena iz Rhizopus niveus za uporabu u razgradnji želatiniziranog škroba u sastavne šećere
§173.120 Karbohidraza i celulaza dobiveni iz Aspergillus niger za uporabu u preradi školjki i račića
§173.130 Karbohidraza izvedena iz Rhizopus oryzae za uporabu u proizvodnji dekstroze iz škroba
§173.135 Katalaza izvedena iz Micrococcus lysodeikticus za uporabu u proizvodnji sira
§173.140 Esteraza-lipaza izvedena iz Mucor miehei var. Cooney et Emerson kao pojačivač okusa u sirevima, mastima i uljima te mliječnim proizvodima
§173.145 Alfa-galaktozidaza izvedena iz Morteirella vinaceae var. rafinoseutilizator za uporabu u proizvodnji saharoze iz šećerne repe
§173.150 Enzimi za zgrušavanje mlijeka, mikrobni za upotrebu u proizvodnji sira (Enzimi za zgrušavanje mlijeka dobiveni su iz Endothia parasitica, Bacillus cereus, Mucor pusillus Lindt i Mucor miehei i Aspergillus oryzae modificiran tako da sadrži gen za asparaginsku proteinazu iz Rhizomucor miehei var Cooney et Emerson
§173.160 Candida guilliermondii kao organizam za fermentaciju proizvodnje limunske kiseline
§173.165 Candida lipolytica za fermentacijsku proizvodnju limunske kiseline.
§173.280 Postupak ekstrakcije otapalom za oporabu limunske kiseline iz Aspergillus niger fermentacijski liker

Slijedi kompilacija tvari potvrđenih GRAS -om navedenih u 21 CFR -u, dio 184, koje potječu od mikroorganizama. Ovaj popis uključuje i izvore morskih algi. Uvjeti za njihovu uporabu propisani su u referentnim propisima i temelje se na upotrebi nepatogenih i netoksikogenih sojeva dotičnih organizama te na korištenju trenutne dobre proizvodne prakse (184.1 (b)). Imajte na umu da nisu sve GRAS tvari zabilježene kao takve, pa ovo ne predstavlja potpuni popis svih sastojaka hrane dobivenih iz mikroba.

Tablica 2. Tvari dobivene iz mikroorganizama koje je FDA potvrdila kao općenito priznate kao sigurne u 21 CFR184
Odjeljak u 21 CFR Sastojak ili tvar
§184.1005 Octena kiselina može se dobiti fermentacijom
§184.1011 Alginska kiselina napravljena od određenih smeđih algi
§184.1012 Pripravak enzima alfa-amilaze iz Bacillus stearothermophilus koristi se za hidrolizu jestivog škroba za proizvodnju maltodekstrina i hranjivih zaslađivača ugljikohidrata.
§184.1027 Mješoviti produkt enzima karbohidraze i proteaze dobiven iz Bacillus licheniformis za upotrebu u hidroliziranju proteina i ugljikohidrata u pripremi alkoholnih pića, slatkiša, hranjivih zaslađivača i proteinskih hidrolizata
§184.1061 Mliječna kiselina može se proizvesti fermentacijom
§184.1081 Propionska kiselina iz bakterijske fermentacije
§184.1115 Agar-agar, ekstrahiran iz niza srodnih vrsta klase crvenih algi Rhodophyceae
§184.1120 Smeđe alge, koje će se koristiti osušene kao pojačivač okusa, su morske alge ove vrste: Analipus japonicus, Eisenia bicyclis, Hizikia fusiforme, Kjellmaniella gyrata, Laminaria angustata, Laminaria longirruris, Laminaria Longissima, Laminaria ochotensis, Laminaria claustonia, Laminaria saccharina, Laminaria digitata, Laminaria japonica, Macrocystis pyrifera, Petalonia fascia, Scytosiphon lome
§184.1121 Crvene alge, koje će se koristiti osušene kao pojačivač okusa, su morske alge ove vrste: Gloiopeltis furcata, Porphyra crispata, Porhyra deutata, Porhyra perforata, Porhyra suborbiculata, Porphyra tenera, Rhodymenis palmata
§184.1133 Amonijev alginat iz određenih smeđih algi
§184.1187 Kalcijev alginat iz određenih smeđih algi
§184.1318 Glucono delta-lakton, oksidacijom D-glukoze mikroorganizmima koji su nepatogeni i netoksikogeni za čovjeka ili druge životinje. To uključuje, ali nije ograničeno na njih Aspergillus niger i Acetobactor suboxydans
§184.1372 Netopljivi enzimski pripravci glukoze izomeraze dobivaju se od priznatih vrsta precizno klasificiranih, nepatogenih i netoksikogenih mikroorganizama, uključujući Streptomyces rubiginosus, Actinoplane missouriensis, Streptomyces olivaceus, Streptomyces olivochromogenes, i Bacillus coagulans uzgojeno u fermentaciji čiste kulture koja ne proizvodi antibiotike
§184.1387 Priprema enzima laktaze iz Candida pseudotropicalis za upotrebu u hidrolizi laktoze u glukozu i galaktozu
§184.1388 Priprema enzima laktaze iz Kluyveromyces lactis (prethodno zvan Saccharomyces lactis) za upotrebu u hidrolizi laktoze u mlijeku
§184.1420 Enzimski preparat lipaze iz Rhizopus niveus koristi se u interesterifikaciji masti i ulja.
§184.1538 Nisin priprema od Lactococcus lactis Lancefield Grupa N za uporabu kao antimikrobno sredstvo za inhibiranje rasta Clostridium botulinum stvaranje spora i toksina u pasteriziranim sirnim namazima.
§184.1610 Kalijev alginat, kalijeva sol alginske kiseline, dobivena iz određenih smeđih algi
§184.1685 Siriš (životinjskog podrijetla) i pripravak kimozina iz Escherichia coli K-12, Kluyveromyces marxianus var. lactis ili Aspergillus niger var. awamori za zgrušavanje mlijeka u sirevima i drugim mliječnim proizvodima
§184.1695 Biosintetiziran ribobovinom Eremothecium ashbyii
§184.1724 Natrijev alginat, natrijeva sol alginske kiseline, dobivena iz određenih smeđih algi
§184.1848 Početni destilat od maslaca iz mliječnih kultura Streptococcus lactis, Streptococcus cremoris. Streptococcus lactis podvrsta diacetilaktis, Leuconostoc citovorum, Leuconostoc dextranicum
§184.1924 Priprema enzima ureaze iz Lactobacillus fermentum za uporabu u proizvodnji vina
§184.1945 Vitamin B12 iz Streptomyces griseus
§184.1950 Vitamin D, proizveden ultraljubičastim zračenjem ergosterola izoliranog iz kvasca i srodnih gljiva
§184.1983 Ekstrakt pekarskog kvasca iz Saccharomyces cerevisiae
§184.1985 Pripravak enzima aminopeptidaze iz Lactococcus lactis koristi se kao izborni sastojak za razvoj okusa u proizvodnji cheddar sira.

Sljedeće tvari potvrđene GRAS -om navedene su u 21 CFR -u, dio 186, i potvrđene su za upotrebu kao tvari koje se posredno dodaju hrani. Uvjeti za njihovu uporabu propisani su u referentnim propisima i temelje se na upotrebi nepatogenih i netoksikogenih sojeva dotičnih organizama te na korištenju trenutne dobre proizvodne prakse (186.1 (b)).

Tablica 3. Tvari dobivene iz mikroorganizama koje je FDA potvrdila kao općenito priznate kao sigurne za neizravnu uporabu u 21 CFR186
Odjeljak u 21 CFR Tvar
§186.1275 Dekstrani, dobiveni fermentacijom saharoze pomoću Leuconostoc mezenteroidi soj NRRL B-512 (F)
§186.1839 Sorboza, nastala oksidacijom sorbitola pomoću Acetobacter xylinum ili po Acetobacter suboxydans

Slijedi kompilacija enzima dobivenih mikrobima koje je FDA priznala kao GRAS u dopisima mišljenja objavljenim početkom 1960 -ih. Mišljenja se temelje na upotrebi nepatogenih i netoksikogenih sojeva odgovarajućih organizama te na korištenju postojeće dobre proizvodne prakse.

Tablica 4. Tvari dobivene iz mikroorganizama koje je FDA priznala kao općenito priznate kao sigurne u pismu mišljenja
Enzim
Karbohidraza, celulaza, glukoza oksidaza-katalaza, pektinaza i lipaza iz Aspergillus niger
Karbohidraza i proteaza iz Aspergillus oryzae
Karbohidraza i proteaza iz Bacillus subtilis
Invertaza iz jestivog pekarskog kvasca ili pivskog kvasca (Saccharomyces cerevisiae)

Slijedi zbirka hrane za prehranu ljudi navedena u 21 CFR -u 131, 133, 136 i 137 koje mogu sadržavati ili biti izvedene iz mikroorganizama.

Tablica 5. Hrana za ljudsku prehranu koja može sadržavati ili biti dobivena iz mikroorganizama navedenih u 21 CFR -u, dijelovima 131, 133, 136 i 137
Odjeljak u 21 CFR Standardizirana hrana
§131.111 Zakiseljeno mlijeko, sa ili bez dodatka karakterističnih mikroorganizama, i mikrobna kultura koja proizvodi aromu i okus. Uvjeti za njihovu uporabu propisani su u referentnim propisima
§131.200 Jogurt napravljen od bakterija koje proizvode mliječnu kiselinu Lactobacillus bulgaricus i Streptococcus thermophilus
§131.106 Plavi sir, karakteriziran prisutnošću plijesni Penicillium roquefortii
§133.113 Cheddar sir, podvrgnut djelovanju bakterijske kulture koja proizvodi mliječnu kiselinu i enzima zgrušavanja životinjskog, biljnog ili mikrobnog podrijetla koji se koriste u stvrdnjavanju ili razvoju okusa
§136.110 Kruh, peciva i lepinje mogu kao opcionalne sastojke sadržavati bakterije koje proizvode mliječnu kiselinu
§137.105 Brašno može sadržavati alfa-amilaze dobivene iz gljive Aspergillus oryzae

Prethodne su sankcije odobrene za uporabu bezopasnih bakterija koje proizvode mliječnu kiselinu, kao npr Lactobacillus acidophilus, kao izborni sastojci u specificiranoj standardiziranoj hrani. Ove su bakterije dopuštene za uporabu u uzgojenom mlijeku (koje uključuje mlaćenicu) (§ 131.112), kiselom vrhnju (§ 131.160), svježem siru (§ 133.128) i jogurtu (§ 131.200), pod uvjetom da su obavezne kulture Lactobacillus bulgaricus i Streptococcus thermophillus koriste se i u jogurtu.


Perspektivna udružena studija o osjetljivosti na hranu i alergijama na hranu u ranom djetinjstvu na razini čitavog mikrobioma

Pozadina: Promjene u crijevnom mikrobiomu prospektivno su povezane s razvojem astme, a manje je poznato o ulozi promjena mikrobioma u razvoju alergije na hranu.

Metode: Uzorci crijevnog mikrobioma prikupljeni su u dobi od 3-6 mjeseci u djece koja su sudjelovala u fazi praćenja interventnog ispitivanja visokih doza vitamina D danog tijekom trudnoće. U dobi od 3 godine procijenjena je osjetljivost na hranu (mlijeko, jaja, kikiriki, soja, pšenica, orah). Alergija na hranu definirana je kao izvještaj skrbnika o alergiji koju je zdravstveni radnik dijagnosticirao na gore navedenu hranu prije treće godine s dokazima senzibilizacije na IgE. Analiza je provedena pomoću Phyloseq-a i DESeq2 P-vrijednosti su prilagođene za više usporedbi.

Rezultati: Dostupni su potpuni podaci za 225 djece, bilo je 87 slučajeva preosjetljivosti na hranu i 14 slučajeva alergije na hranu. Mjere raznolikosti mikroba nisu se razlikovale između slučajeva i kontrola senzibilizacije hrane i alergije na hranu. Rodovi Haemophilus (log2 promjena nabora -2,15, P =, 003), Dialister (zapisnik2 promjena nabora -2,22, P =, 009), Dorea (zapisnik2 promjena nabora -1,65, P =, 02) i Clostridium (log2 višestruka promjena -1,47, P =, 002) bili su nedovoljno zastupljeni među ispitanicima sa osjetljivošću na hranu. Rodovi Citrobacter (log2 promjena nabora -3,41, P =, 03), Oscillospira (log2 promjena nabora -2,80, P =, 03), Lactococcus (log2 promjena nabora -3,19, P = 0,05) i Dorea (zapisnik2 višestruka promjena -3,00, P =, 05) bili su nedovoljno zastupljeni među ispitanicima s alergijom na hranu.

Zaključci: Vremenska povezanost između kolonizacije bakterija, senzibilizacije na hranu i alergije ukazuje na to da mikrobiom može imati uzročnu ulogu u razvoju alergije na hranu. Naši nalazi imaju terapeutske implikacije za prevenciju i liječenje alergije na hranu.

Ključne riječi: Dorea mikrobiom osjetljiv na hranu alergija na hranu.

© 2017 EAACI i John Wiley i sinovi A/S. Nakladnik John Wiley and Sons Ltd.


46: Mikrobna hrana - Biologija

Mikrobna ekologija proučava mikrobe u okolišu i njihovu međusobnu interakciju. Mikrobi su najmanja stvorenja na Zemlji, no unatoč svojoj maloj veličini, imaju veliki utjecaj na nas i na naš okoliš.
Mikrobna ekologija može pomoći u odgovoru na neka od naših najpraktičnijih pitanja, poput "Kako možemo poboljšati svoj život?" kao i osnovna pitanja poput "Zašto smo ovdje?"

Mikrobna ekologija može nam pokazati naše mjesto u kozmosu - kako je život nastao i kako se razvio, te kako smo povezani s velikom raznolikošću svih drugih organizama.

Proučavanje ekologije mikroba može nam pomoći da poboljšamo svoj život upotrebom mikroba u obnovi okoliša, proizvodnji hrane, bioinženjeringu korisnih proizvoda poput antibiotika, dodataka prehrani i kemikalija. Proučavanje ovih bizarnih i raznolikih stvorenja kojih ima posvuda, a nigdje ih nije vidjeti, fascinantno je i bavljenje znatiželjom i razigranošću u nama.

Većina vrsta mikroba ostaje nepoznata. Procjenjuje se da poznajemo manje od 1% mikrobnih vrsta na Zemlji. Ipak, mikrobi nas okružuju posvuda - zrak, voda, tlo. Prosječan gram tla sadrži milijardu (1.000.000.000) mikroba koji predstavljaju vjerojatno nekoliko tisuća vrsta.

Mac, moćni mikrob može biti minimalan, ali ovaj čudesni mikrob i njegovi sluge utječu na nas i našu okolinu na mnogo načina.


Dizajniraj-izgradi-testiraj-nauči

Naše kompetencije iz područja bioloških znanosti omogućuju nam pronalaženje, stvaranje i primjenu ovih mikroba i enzima za stvaranje održivijih procesa, sastojaka i gradivnih elemenata za nove proizvode. Konkretno, oni nam pomažu da detaljno osmislimo i karakteriziramo enzime i mikrobne sojeve do molekularne razine kako bismo procijenili njihovu učinkovitost u uvjetima primjene te razvili podatkovne i računalne modele za izgradnju učinkovitih inženjerskih ciklusa "projektiraj-izgradi-testiraj-nauči" .


46: Mikrobna hrana - Biologija

POSTUPCI MIKROBNIH ISPITIVANJA

1. Ispitivanje hrane na prisutnost, vrste i broj MO i/ili njihovih metabolita temelj je mikrobiologije hrane.

2. Prilikom korištenja ovih tehnika važno je zapamtiti da zbog specifičnih zahtjeva rasta ili ograničenja među različitim MO, niti jedna od uobičajeno korištenih metoda neće dati točan broj MO u hrani.

3. U slučaju nekih patogeni organizmi ili njihovi toksini, jednostavno želite znati bez obzira jesu li prisutni ili ne.

Prva odluka za vrijeme mikrobiološkog ispitivanja hrane je:

b. Homogenizirani uzorak hrane.

Iako će većina uzoraka hrane biti homogenizirana, u nekim namirnicama, poput komada cijelog mesa gdje je unutrašnjost uglavnom sterilna, površinski uzorak može biti značajniji jer će homogenizacija uključivati ​​dijelove hrane koji ne sadrže MO i razrijeđene rezultate.

Druge primjene u kojima su površinska mjerenja važna u MO testiranju uključuju površine u pogonu u kontaktu s hranom.

Iako oporavak svih mikroorganizama s površine možda nije uvijek moguć, dosljedno praćenje određenih područja u prehrambenom pogonu površinskim ispitivanjem pruža vrijedan uvid u relativnu čistoću tog područja.

1. Brisanje – MO prikupljeni s površine sterilnim tamponom od pamuka ili kalcijevog alginata (alginatni brisevi su najbolji jer se alginat može lako otopiti u heksametafosfatu), prenijeti u juhu gdje se izbacuju, zatim razrijediti i upotrijebiti za daljnja ispitivanja kako bi se utvrdilo ukupno brojevima. Spužve se mogu upotrijebiti za brisanje većih površina, a zatim se stavljaju u vrećicu napunjenu tamponom.

c. Dobro prilagođen fleksibilnim, neravnim i jako onečišćenim površinama

1. Oporavak MO može biti loš (10% u nekim studijama, ali čak je i to još uvijek prihvatljivo za mnoge primjene)

2. Kontaktne ploče (Rodac ploče) – podignuta agar ploča koja se pritisne na površinu i zatim inkubira.

1. Metoda izbora za glatke, čvrste i neporozne površine (npr. Kade u sirani)

2. Mogu se koristiti bilo koje vrste medija

1. Rast kolonija otežava popisivanje na jako zagađenim površinama

2. Uklanja samo oko 0,1% kontaktne flore - mnogo manje od briseva

Modificirana verzija ove tehnike je agar štrcaljka ili kobasica. Epruveta puna agara, uzorci se pritisnu na površinu, a zatim izrežu na Petrijevu ploču za inkubaciju.

3. Metoda izrezivanja – iz hrane se uzima utikač poznate površine, a zatim se s kraja površine uzima 1-3 mm, homogenizira i platira kako bi se odredio ukupan broj. Obično se koristi za rezanje cijelog mesa.

1. Miješalica – sada se ne koristi tako opsežno (vidi razloge navedene u nastavku)

2. Colwell stomacher je metoda izbora.

Hrana se stavlja u sterilnu plastičnu vrećicu s razrjeđivačem, a zatim se ubacuje u stroj. Stomak ima dvije lopatice koje snažno ometaju hranu i daju lijepu homogenu tekućinu za uzorkovanje.

Prednosti u odnosu na blendere uključuju:

1. Nema čišćenja jer je hrana u vrećici

2. Nema nakupljanja topline koje će ozlijediti Mo (bolje preživljavanje u uzorku)

3. Homogenati se mogu zamrznuti u vrećama ako je potrebno za daljnju uporabu

C. METODE UTVRĐIVANJA UKUPNO MIKROBNIH BROJEVA

Nakon što se uzorak pripremi, na raspolaganju je nekoliko metoda za određivanje ukupnog broja stanica u hrani. Mnoge od ovih metoda također omogućuju nabrajanje važnih skupina bakterija, poput koliformnih. Nekoliko vam može omogućiti da prebrojite broj mikroba iz određenog roda poput Salmonela.

1. Standardni broj ploča (SPC) Daleko najraširenija metoda za određivanje broja održivih jedinica za formiranje kolonija (CFU) u hrani. Koristite tanjur za namazanje ili sipanje (psihrotrofi možda neće preživjeti ni na tanjurima za sipanje) koji uključuje homogenizirani uzorak hrane. Inkubacija je aerobna na 35 o C tijekom 48 2 h.

Broj APC –aerobnih ploča – stanice se šire po površini agara i inkubiraju aerobno.

2. AOAC (Izv. Službeni analitički kemičari) odobren za mnoge namirnice

1. Rezultati nisu dostupni najmanje 16-18 sati (često i dulje)

2. Na broj hrane u hrani utječe nekoliko čimbenika, uključujući:

a. Metoda uzorkovanja i raspodjela MO u hrani

b. Priroda prehrambene flore (uglavnom dobiva mezofilne i fak. Aerobe)

d. Unutarnji parametri medija za rast odražavaju otkrivene MO

e. Vrijeme i temperatura inkubacije (vanjski parametri)

f. Mikrobni antagonizam među vrstama u hrani

2. Brojač spiralnih ploča – Automatizirana verzija SPC -a je spiralni plater, uređaj koji distribuira kontinuirano opadajući volumen tekućine preko jedne rotirajuće agar ploče (ruka za doziranje se pomiče poput igle na gramofonu, samo unatrag). Zatim se agar inkubira i vrši se prebrojavanje.

-Može učinkovito isporučiti do 10 5 koncentracijskog raspona na jednoj ploči, ali nabrajanje zahtijeva posebnu tablicu za brojanje.

1. Lako se izvodi (potrebno je malo treninga)

2. Koristi se manje materijala (ploče s agarom, razrjeđivači, pipete)

3. 3-4 sata više uzoraka može se pokrenuti po satu

4. Spiralna oplata dobro se slaže sa vrijednostima SPC i metoda je AOAC.

1. Čestice hrane mogu začepiti držač za točenje – prikladniji za tekućine poput mlijeka

Dva plastična filma koja se drže zajedno s jedne strane i premazana poput sendviča

sastojci medijuma za kulturu, tetrazolijeva boja (reducirajuća boja) i voda

topljivo sredstvo za želiranje. 1 ml uzorka u razrjeđivaču stavlja se između filmova i lagano razvlači pritiskom na dvije strane filma. Nakon inkubacije, rast stanica smanjuje boju i daje crvene kolonije.

1. u filmovima su dostupni neselektivni i selektivni mediji. Dostupni su filmovi za izvođenje ukupnog broja bakterija ili gljivica u ploči, broja koliformnih biljaka i specifičnih testova na hemoragiju E coli 0157: H7

2. proizvod ima AOAC odobrenje

3. store for long periods, no autoclave required

2. difficult to read without training

4. Most Probable Numbers : A method based upon statistical probability. Food samples are prepared like SPC. Three serial dilutions are prepared and then transferred to 9 or 15 tubes (3- or 5-tube method). The numbers of organisms/g are then estimated using standard MPN tables.

2. results from one lab more likely than SPC to agree with those from another lab

3. specific groups of organisms (e.g. coliforms-it is the method of choice) can be enumerated using different selective medias

4. AOAC for coliforms, S. aureus & pojačalo B. cereus (many others) in various foods

1. lots of tubes required (clean up intensive)

2. lack of precision, generally higher than SPC results

1. Most useful for microscopic examination of water supplies (e.g. coliform counts) since most foods will clog the filters. 0.45 m-pore filters allow water to pass but trap bacteria.

2. Filters are especially useful for samples with low numbers of bacteria since large volumes of fluid can be passed through.

3. Polycarbonate filters are better than the cellulose one because bacteria are caught on the filter surface more efficiently.

4. A given volume of fluid is passed through the filter:

a. the membrane is placed on an agar plate and incubated

b. Direct Microscopic Count ( DMC) can be made on the filter

DMC on filters has been simplified by the use of fluorescent dyes that bind to bacteria.

1. Called the Direct Epifluorescent Filter Technique (DEFT), this method uses dyes and fluorescent microscopy to rapidly enumerate bacteria on a filter.

2. This procedure includes a pre-filtering step to remove large food particles (-if necessary-5 m filter used) and then the filtrate is treated with a detergent and a protease to degrade somatic cells that will clog the small 0.6 m polycarbonate filter used next.

3. The filter is stained with acridine orange, dried and then counted by epifluorescent microscopy.

4. Results are available in less than 30 minutes.

2. morph can be determined

3. repeatability is better than SPC

4. solid foods can be examined using the prefiltration step

2. can t tell live from dead cells

3. food parts sometimes look like cells

4. cells are usually not distributed evenly

5. different MO don t stain equally

Hydrophobic Grid Membrane Filters (HGMF)

1. A special filter that contains 1,600 wax grids that restrict colony growth to single grids.

2. 10 to 9 x 10 4 cells can be enumerated on a single filter using a Most Probable Numbers statistical procedure.

3. Homogenized food is passed through the filter and then it is placed on an agar plate and incubated overnight.

4. The colonies are counted and then MPN is calculated.

1. can detect as few as 10 CFU/g

2. can enumerate total CFU or specific groups (coliforms, fungi, pseudomonads, salmonellae)

3. AOAC approval for total coliforms, fecal coliforms and salmonellae

6. Dye Reduction : Supernatants of food are added to standard solutions of methylene blue or resazurin:

a. Blue --> White for reduction of methylene blue

b. Slate blue --> pink or white for resazurin

The time required for dye reduction is inversely proportional to the total number of microorganisms.

Technique lends itself to automation and has a long history of use in dairy foods.

Developed an automated colorimeter that has AOAC approval for determination of total counts and coliforms.

1. simple, rapid and inexpensive

2. only viable cells reduce dye

1. not all MO reduce dye equally well

2. Some foods like meat contain high levels of natural reductants that cloud results. Use of a stomacher instead of a blender to homogenize meat has been shown to reduce this problem. Apparently the stomacher doesn t release as much NADH or other reductants from the tissue.

7. Impedancija: Impedance is a measurement based on the resistance in an electric circuit to the flow of alternating current. Microorganisms metabolize substrates of low conductivity into products of higher conductivity. As a result, resistance decreases with growing cell numbers. With proper instruments, the change in impedance can be followed and used to detect as few as 10 to 100 cells in a sample within about 6 h (impedance detection time or IDT). The technique is faster than SPC and gives results that are within 90-95% agreement with the former technique but is not AOAC approved.

Special concern metabolically injured cells :

1. Processing conditions often include treatments such as mild heating or cooling steps (and many others) that injure but do not kill microorganisms.

2. Metabolically injured cells (MI) may not grow well on plate count agar and thus leave you with the impression that your processing step is killing more MO than it really does and that the food contains fewer MO than it actually does (since these cells will eventually recover and grow in the food if conditions are favorable).

3. If you work for a company that is using a food process where MI cells may be present, then it is useful to include a recovery step for MI cells in your microbial testing procedure.

4. In general, rich media, sometimes supplemented with piruvat ili catalase, favor the recovery of MI cells.

Pyruvate and catalase degrade peroxidases and it is thought that MI cells lack the ability to degrade these toxic oxygen derivatives.

Technique to enumerate MI cells :

1. plate food samples on normal (minimal and rich media)

2. add an extra day of incubation time

3. comparison between media (plates) – Rich media will include MI and uninjured cells, minimal will only have uninjured cells. This will give you an idea of how effective your processing step is on killing MO.

D. Molecular Methods to Detect Bacteria or Metabolites:

1. Except for those applications that involve coliform or Salmonella enumeration, the methods we have examined thus far are primarily intended to predict product shelf life and prevent spoilage.

2. The next group of testing procedures is instead designed to detect specific genera or species of food-borne pathogens (or their metabolites).

3. Unfortunately, many of these tests employ expensive reagents and because of the expense, their use is generally (but not always) more diagnostic than preventative (i.e. used only after an outbreak).

1. Oligonucleotide DNA Probes - This test is based on DNA or DNA-RNA complementary base pairing or hybridization.

-Go through a hybridization procedure include colony hyb (can run up to 69 filter w/48 CFU per filter in one Rxn), dot blots or blots of restriction digests.

-can use radioactive or non-isotopic labels on probes. Reactions can require anywhere from 10 h - 2 days.

This technique requires that the sequence of the target nucleic acid (frequently a gene for toxin production or a species-specific 16S rRNA sequence) be determined and unique to the organisms sought. As we discussed earlier in the lectures on taxonomy, 16S rRNA contains widely conserved as well as species (and sometimes subspecies) -specific regions. Probes to the species-specific regions are used to detect particular bacteria such as Salmonella. One advantage to targeting the 16S rRNA versus a DNA sequence in the chromosome is that there are several copies of the 16S rRNA per cell. The same advantage applies to genes located on multicopy plasmids. Gene probes may be based on the DNA sequence of particular toxins such as Clostridium perfringens or staphylococcal enterotoxins. At lease one test for Salmonela has AOAC approval.

2. Polymerase Chain Reaction (PCR-DNA Amplification). This technique is more useful than DNA probing when small numbers of a particular microbe are present. It can amplify a single copy of any DNA sequence 10 7 times within a few hours. Amplified DNA can then be detected by agarose gel electrophoresis or hybridization.

-PCR requires primers based on the known nucleic acid sequence of the amplification target.

PCR has been used to detect 1-5 CFU of E. coli in 100 ml of water, useful for any organism where a unique nucleic acid sequence is known, also for diagnosis by amplification of 16s rRNA (ASM handout new vistas for bacteriologists).

-Vrlo powerful tool with many, many applications the latest clinical manual for diagnostic microbiology is almost completely based on PCR assays.

3. Enzyme-Linked Immunosorbant Assay (ELISA). Another very powerful technique that uses mono- or polyclonal antibodies to detect specific antigens in a sample.

Commercial ELISA kits are available for a variety of applications (e.g. home pregnancy tests) including the detection of various microbes including Salmonella, S. aureus and its enterotoxins, molds and mycotoxins, botulinal toxins and E. coli strains and toxins.

4. Immunoprecipitation (Immunodiffusion) - Another immunological technique commonly used for toxin identification. Several variations but the basic principle involves a reaction between antigen (toxin) and antibody that forms a precipitate in an agar gel.

Immunodiffusion methods can detect as little as 0.1-0.01 g of toxin. Incubation times increase with smaller amounts of antigen (1-6 d range).

In summary, when it comes to selecting a microbial testing procedure, remember the following: QUICK, ACCURATE, CHEAP (choose any two)


SOIL BIOLOGY AND THE LANDSCAPE

An incredible diversity of organisms make up the soil food web. They range in size from the tiniest one-celled bacteria, algae, fungi, and protozoa, to the more complex nematodes and micro-arthropods, to the visible earthworms, insects, small vertebrates, and plants.

As these organisms eat, grow, and move through the soil, they make it possible to have clean water, clean air, healthy plants, and moderated water flow.

There are many ways that the soil food web is an integral part of landscape processes. Soil organisms decompose organic compounds, including manure, plant residue, and pesticides, preventing them from entering water and becoming pollutants. They sequester nitrogen and other nutrients that might otherwise enter groundwater, and they fix nitrogen from the atmosphere, making it available to plants. Many organisms enhance soil aggregation and porosity, thus increasing infiltration and reducing runoff. Soil organisms prey on crop pests and are food for above-ground animals.

The soil environment. Organisms live in the microscale environments within and between soil particles. Differences over short distances in pH, moisture, pore size, and the types of food available create a broad range of habitats.

Credit: S. Rose and E.T. Elliott. Please contact the Soil and Water Conservation Society at [email protected] for assistance with copyrighted (credited) images.

The Food Web: Organisms and Their Interaction

The soil food web is the community of organisms living all or part of their lives in the soil. A food web diagram shows a series of conversions (represented by arrows) of energy and nutrients as one organism eats another.

All food webs are fueled by the primary producers: the plants, lichens, moss, photosynthetic bacteria, and algae that use the sun's energy to fix carbon dioxide from the atmosphere. Most other soil organisms get energy and carbon by consuming the organic compounds found in plants, other organisms, and waste by-products. A few bacteria, called chemoautotrophs, get energy from nitrogen, sulfur, or iron compounds rather than carbon compounds or the sun.

As organisms decompose complex materials, or consume other organisms, nutrients are converted from one form to another, and are made available to plants and to other soil organisms. All plants - grass, trees, shrubs, agricultural crops - depend on the food web for their nutrition.

What Do Soil Organisms Do?

Growing and reproducing are the primary activities of all living organisms. As individual plants and soil organisms work to survive, they depend on interactions with each other. By-products from growing roots and plant residue feed soil organisms. In turn, soil organisms support plant health as they decompose organic matter, cycle nutrients, enhance soil structure, and control the populations of soil organisms including crop pests.

Organic Matter Fuels the Food Web

Organic matter is many different kinds of compounds - some more useful to organisms than others. In general, soil organic matter is made of roughly equal parts humus and active organic matter. Active organic matter is the portion available to soil organisms. Bacteria tend to use simpler organic compounds, such as root exudates or fresh plant residue. Fungi tend to use more complex compounds, such as fibrous plant residues, wood and soil humus.

Intensive tillage triggers spurts of activity among bacteria and other organisms that consume organic matter (convert it to CO2), depleting the active fraction first. Practices that build soil organic matter (reduced tillage and regular additions of organic material) will raise the proportion of active organic matter long before increases in total organic matter can be measured. As soil organic matter levels rise, soil organisms play a role in its conversion to humus - a relatively stable form of carbon sequestered in soils for decades or even centuries.

Soil organic matter is the storehouse for the energy and nutrients used by plants and other organisms. Bacteria, fungi, and other soil dwellers transform and release nutrients from organic matter. These microshredders, immature oribatid mites, skeletonize plant leaves. This starts the nutrient cycling of carbon, nitrogen, and other elements.

Credit: Roy A. Norton, College of Environmental Science & Forestry, State University of New York. Please contact the Soil and Water Conservation Society at [email protected] for assistance with copyrighted (credited) images.

Food Sources for Soil Organisms

"Soil organic matter" includes all the organic substances in or on the soil. Here are terms used to describe different types of organic matter.

  • Living organisms: Bacteria, fungi, nematodes, protozoa, earthworms, arthropods, and living roots.
  • Dead plant material organic material detritus surface residue: All these terms refer to plant, animal, or other organic substances that have recently been added to the soil and have only begun to show signs of decay. Detritivores are organisms that feed on such material.
  • Active fraction organic matter: Organic compounds that can be used as food by microorganisms. The active fraction changes more quickly than total organic matter in response to management changes.
  • Labile organic matter: Organic matter that is easily decomposed.
  • Root exudates: Soluble sugars, amino acids and other compounds secreted by roots.
  • Particulate organic matter (POM) or Light fraction (LF) organic matter: POM and LF have precise size and weight definitions. They are thought to represent the active fraction of organic matter which is more difficult to define. Because POM or LF is larger and lighter than other types of soil organic matter, they can be separated from soil by size (using a sieve) or by weight (using a centrifuge).
  • Lignin: A hard-to-degrade compound that is part of the fibers of older plants. Fungi can use the carbon ring structures in lignin as food.
  • Recalcitrant organic matter: Organic matter such as humus or lignin-containing material that few soil organisms can decompose.
  • Humus or humified organic matter: Complex organic compounds that remain after many organisms have used and transformed the original material. Humus is not readily decomposed because it is either physically protected inside of aggregates or chemically too complex to be used by most organisms. Humus is important in binding tiny soil aggregates, and improves water and nutrient holding capacity.

Where Do Soil Organisms Live?

The organisms of the food web are not uniformly distributed through the soil. Each species and group exists where they can find appropriate space, nutrients, and moisture. They occur wherever organic matter occurs - mostly in the top few inches of soil (see graph below), although microbes have been found as deep as 10 miles (16 km) in oil wells. Soil organisms are concentrated:

Around roots. The rhizosphere is the narrow region of soil directly around roots. It is teeming with bacteria that feed on sloughed-off plant cells and the proteins and sugars released by roots. The protozoa and nematodes that graze on bacteria are also concentrated near roots. Thus, much of the nutrient cycling and disease suppression needed by plants occurs immediately adjacent to roots.

In litter. Fungi are common decomposers of plant litter because litter has large amounts of complex, hard-to-decompose carbon. Fungal hyphae (fine filaments) can "pipe" nitrogen from the underlying soil to the litter layer. Bacteria cannot transport nitrogen over distances, giving fungi an advantage in litter decomposition, particularly when litter is not mixed into the soil profile. However, bacteria are abundant in the green litter of younger plants which is higher in nitrogen and simpler carbon compounds than the litter of older plants. Bacteria and fungi are able to access a larger surface area of plant residue after shredder organisms such as earthworms, leaf-eating insects, millipedes, and other arthropods break up the litter into smaller chunks.

On humus. Fungi are common here. Much organic matter in the soil has already been decomposed many times by bacteria and fungi, and/or passed through the guts of earthworms or arthropods. The resulting humic compounds are complex and have little available nitrogen. Only fungi make some of the enzymes needed to degrade the complex compounds in humus.

On the surface of soil aggregates. Biological activity, in particular that of aerobic bacteria and fungi, is greater near the surfaces of soil aggregates than within aggregates. Within large aggregates, processes that do not require oxygen, such as denitrification, can occur. Many aggregates are actually the fecal pellets of earthworms and other invertebrates.

In spaces between soil aggregates. Those arthropods and nematodes that cannot burrow through soil move in the pores between soil aggregates. Organisms that are sensitive to desiccation, such as protozoa and many nematodes, live in water-filled pores.

Bacteria are abundant around this root tip (the rhizosphere) where they decompose the plentiful simple organic substances.

Credit: No. 53 from Soil Microbiology and Biochemistry Slide Set. 1976 J.P. Martin, et al., eds. SSSA, Madison WI. Please contact the Soil and Water Conservation Society at [email protected] for assistance with copyrighted (credited) images.

When Are They Active?

The activity of soil organisms follows seasonal patterns, as well as daily patterns. In temperate systems, the greatest activity occurs in late spring when temperature and moisture conditions are optimal for growth. However, certain species are most active in the winter, others during dry periods, and still others in flooded conditions.

Not all organisms are active at a particular time. Even during periods of high activity, only a fraction of the organisms are busily eating, respiring, and altering their environment. The remaining portion are barely active or even dormant.

Many different organisms are active at different times, and interact with one another, with plants, and with the soil. The combined result is a number of beneficial functions including nutrient cycling, moderated water flow, and pest control.

The Importance of the Soil Food Web

The living component of soil, the food web, is complex and has different compositions in different ecosystems. Management of croplands, rangelands, forestlands, and gardens benefits from and affects the food web. The next unit of the Soil Biology Primer, The Food Web & Soil Health, introduces the relationship of soil biology to agricultural productivity, biodiversity, carbon sequestration and to air and water quality. The remaining six units of the Soil Biology Primer describe the major groups of soil organisms: bacteria, fungi, protozoa, nematodes, arthropods, and earthworms.


Practical Food Microbiology

"Food microbiology has a vital role in our safety programs. This course steered me in the right direction, and I am now able to formulate a plan for shelf life testing something that's very important for our business and processes."

- David A. Kowalski,
Operations Manager/Food Safety Manager,
Bimmy's LLC

Student Reviews

"This class was exactly what I was looking for. I have some microbiology background, but I needed a short, intensive food micro class. The professors give excellent presentations, interactive and applicable."

- Frank D'Angelo,
Food Lab Practice Coordinator,
Nestle

Student Reviews

"I supply products to Asian markets all along the East Coast so food safety is very important to my business. I heard about this class from FDA inspectors who have taken courses at Rutgers. When the best people train at Rutgers, I know it is the place to learn about food safety."

- Raymond Wong,
President,
Trader Ray LLC

Student Reviews

"The course was very thorough and beneficial. I kept sending messages to my boss during class because I couldn t wait to get back to share what I learned! When the FDA audits our plant, I now can refer to guidelines provided by Rutgers to support our limits. I will also use what I learned to train our plant staff. I recommend this class to anybody working in the food industry!"

- Amy D'Amico,
REHS/Quality Programs Manager,
Foodcomm

Student Reviews

"The Food Microbiology class was very insightful. Our company typically launches approximately 40-60 new products in the US every year. The resources and guidance provided in this class were extensive and should be useful in helping with the continued success and safety of our products. I expect to be sending more staff members to next year s class!"

- Angela Ehlich,
Senior Manager- Quality Assurance,
The Hain Celestial Group

Understanding the what, how, when, and why of food pathogens

If you develop, process, distribute, or sell food for a living, it is crucial to have an understanding of the following food microbiology topics:

  • Which pathogens are most likely to cause trouble
  • When and why they threaten product and customer safety and,
  • How to best manage and control the risks posed by these organisms.

This online Practical Food Microbiology course covers all of these subjects and much more! Our team of expert instructors will take you step-by-step through the science and practice of food safety microbiology.

If you have never taken a food micro class, we will teach you the most critical points for food safety applications. You will learn which environmental factors influence the growth of pathogens and spoilage organisms in food, how to avoid microbial contamination, and how to produce safe food products.

Even if you have experience in the area of food safety microbiology, you will benefit from attending this course! Advance your understanding of when and how to use new and powerful (but often abused and misunderstood) tests, tools, and models. Learn to make better choices by understanding the limits and applicability of data produced, as well as the danger of starting with ill-considered assumptions!

By attending this course, you will also learn how to implement a successful, state-of-the-art HACCP (Hazard Analysis Critical Control Points) system to identify points of contamination risk in the food manufacturing process. Our instructors will cover how to control and monitor those risks and how to take corrective actions. (For more in-depth training on this food safety topic, check out our 3-day HACCP Plan Development for Food Processors course.)

Whether you are looking for an introduction to the subject of food microbiology, need a refresher to strengthen your foundational knowledge of the topic, or are seeking insights to help you solve microbiology problems with your food products, you will leave this course with new information to keep your food products safe.

Microbial Growth in Food - Why is Temperature Important?
Instructor Karl Matthews, PhD provides a preview of what you'll learn in this course.

Read more about what to expect at the Practical Food Microbiology course! Click to expand each section.

  • Microbial Ecology: Food safety depends on understanding what conditions encourage microbial growth and what inhibits it.
  • Pathogens &ndash Gram-negative: The FDA/USDA are hustling to better understand Shiga-toxin producing E. coli (STEC) and Salmonella.
  • Pathogens &ndash Gram-positive: Listeria monocytogenes has plagued many food manufacturers. We focus on ecology and control.
  • Spoilage: Yeast and mold are major culprits in food spoilage. Learn how to detect and identify them in food processing facilities.
  • Current Food Safety Issues: Get the latest on the worst outbreaks to hit the news and consumers' GI tracts.
  • Testing: A good test done wrong can be more dangerous than no testing at all. Know the uses and abuses of microbial testing.
  • Predictive Models & Quantitative Risk Assessment: Tools of quantification are continually expanding in power and applicability.

Don Schaffner, PhD - Distinguished Professor and Extension Specialist, Dept. of Food Science, Rutgers University
Karl Matthews, PhD - Professor, Department Chair, Dept. of Food Science, Rutgers University

Here's what students have to say about the Practical Food Microbiology instructional team:

  • "The way both professors taught from basics to very complicated advanced concepts successfully. Excellent!"
    - Carista Wilson, Lab Information Management Administrator, The Hershey Company, PA, 2014 attendee
  • "Great content and fantastic professors who display the information clearly and in a way everyone can understand."
  • "Both speakers were well knowledgeable and extremely entertaining."
  • "Enjoyed both presentations very informative."
  • "Instructors were very approachable."

Any food industry professional who wants to better understand food safety microbiology will benefit from participating in this training course. Past attendees have included:

  • Food Safety Managers
  • Food Processing Managers and Technicians
  • Food Research and Development Professionals
  • Food Technologists
  • Food Safety Consultants
  • Quality Assurance/Quality Control Professionals
  • Food Service Professionals with Technical Backgrounds
  • Public Health Professionals
  • Practicing Microbiologists
  • Food Product Marketing Managers

"I registered to broaden my knowledge of food spoilage and how to prevent it. I now have a good understanding of spoilage that is very practical for our canning business. Thanks to this class, I will change how cooled can temperature is viewed and handled at my company to make our products even safer. & quot
- Robert Fredericks, Quality Supervisor, Bumble Bee Seafoods, 2015 attendee

"[I enrolled] to better understand the reasons for our micro testing programs. [Most useful was] the reference material. I can look up more information. This course shows how to target our testing."
- Eileen Tenore, Quality Control Systems Chemist, Symrise, NJ, 2014 attendee

"Excellent, I found everything useful. This course reinforced what I do."
- Paul Newton, Quality Control Microbiologist, Takasago International Corporation, NJ, 2014 attendee

"The most useful aspect for me was the detail given about the individual organisms and their ecology. I will use things I learned about microbiology ecology to help improve my sanitation program. & quot
- Tony Richardson, Sanitation Supervisor, Cumberland Dairy Inc, NJ, 2013 attendee

"I work very closely with food science majors this course helped me to continue my development while gaining a better understanding of some of their procedural knowledge and nomenclature allowing me to effectively engage with the team members.& quot
- Vid Lutz, Product Development Chef, Nestle

"Thank you for the excellent 2-day Food Micro course. It was well-planned, well-delivered and very informative. & quot
- Crispin Philpott, Executive Vice-President, FoodChek Systems, Inc., 2011 attendee

& quotExcellent review of pathogens and considerations regarding sampling techniques. I plan to review all recipe directions -- choice of sampling plan has stoked interest in product use hazards assessment."
- G. Toner, Manager Quality Engineering, Rakitt Benckiser, 2011 attendee

& quotVery useful data and professors were open to questions. I can use the material on diseases caused by microorganisms for future employee training."
- I. Manjarres, Quality Assurance Technician, Fratelli Beretta USA, 2011 attendee

The March 16-18, 2021 offering of this course was approved for the following credits. We will reapply for similar credits the next time the course runs, but we cannot guarantee credit approval for future offerings.

In addition to 1.6 Rutgers CEUs, this online food microbiology course is approved for the following credits:

CERTIFIED FOOD SCIENTISTS:
This program qualifies for Certified Food Scientist (CFS) recertification contact hours (CH). CFS Certificants may claim a maximum of 11.75 CH for their participation in this program. For more information, please visit www.ift.org/certification or email [email protected]

HEALTH OFFICERS AND REGISTERED ENVIRONMENTAL HEALTH SPECIALISTS:
Rutgers University, NJAES, Office of Continuing Professional Education has been approved by the New Jersey Department of Health as a provider of NJ Public Health Continuing Education Contact Hours (CEs). Participants who complete this education program will be awarded 13.0 NJ Public Health Continuing Education Contact Hours (CEs).

Substitutions are permitted. View cancellation policy.

No meals will be provided.

This virtual online class will be delivered via Webex. Registrants will receive more information as we move close to the course date and on March 15, 2021, they will receive an email with a link to access the course and a document with tips on how to use Webex. Please log into Webex at 8:45am EDT (15 minutes before start time) for a brief overview of the online format. The course will start promptly at 9:00am EDT.

Equipment you will need to access this training:

  • A computer or tablet
  • Microphones and webcams are required as this is a very interactive course

Photo ID Requirement:

Each registrant will be asked provide a photo of him/herself holding their government-issued photo ID. This is required by credit boards so that you may receive credits for participating in this online course.

  • You will receive a reminder email prior to the start of the class with further instructions. Wait to receive these instructions before you attempt to upload your ID.
  • The photo must be clear enough that we can read your name and verify that the person pictured on the ID is in fact the person holding it.
  • After an OCPE staff member reviews the picture and verifies your identity, you will have access to participate in the course when it begins.

IMPORTANT: A UNIQUE EMAIL ADDRESS IS REQUIRED FOR EACH REGISTRANT TO ACCESS OUR ONLINE COURSES

If this is your first time registering with us, please provide your own unique email address when registering do not provide an email address that you share with co-workers.

If you have previously taken classes with us and have used an email address that you share with your co-workers or supervisor, you must update your account with a unique email address. Click the Register Online button below and sign into your account. On the left side toolbar, click My Account. On the drop-down menu, click Edit Profile/Password. Scroll down to the Email Address field (not the secondary email address field!) and enter your own, individual (not shared!) email address here. Click the podnijeti button at the bottom to save. If you need assistance updating your account, please email or call (848-932-9271, option 2) our Registration Department.

Note: Pre-registration is required.

Overview of Stormwater Management Rules
Adriana Caldarelli, NJDEP - SWM Unit

Stormwater Management Rule Compliance Issues
Pete DeMeo, NJDEP - Land Use Regulation Program

MS4 Program Requirements for Stormwater Management
Elizabeth Dragon, NJDEP - SWM Unit

Best Management Practices & Maintenance Part 1
Adriana Caldarelli, NJDEP - SWM Unit
Corey Anen, NJDEP - SWM Unit

Best Management Practices & Maintenance Part 2
Adriana Caldarelli, NJDEP - SWM Unit
Corey Anen, NJDEP - SWM Unit

Sorry, registration is not currently available for this course.

Would you like to be notified when the next offering is scheduled?
Here are 3 convenient ways to be added to our mailing list:
1. Click here to join our email list (please choose "Food Science & Safety" as your Area of Interest)
2. Call us at 848-932-9271, select option 3
3. E-mail us at [email protected]

Program Coordinator: Suzanne Hills, 848-932-7234
Administrative Assistant: Sarah McCarthy, 848-932-7703

This course is approved by the New Jersey State Approving Agency for Veterans Training for educational benefits through the GI Bill®. For more information about the GI Bill, click here.


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