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Microbialbiotechnologyinthelaboratoryandinpractce
Anessentialconditionforanaerobecultivationistocreateand
thenmaintainanatmospherewithoutmolecularoxygen.The
classificationofanaerobicculturemethodsisbasedprimarilyon
thetypeofproceduresusedtocreateandmaintainanoxygen-
freegrowthenvironment,withparticularemphasisonaspects
suchas:(1)obtainingavacuum,(2)replacingairwithgases
thatdonotcontainmolecularoxygen,(3)oxygenreduction,
(4)absorptionofoxygenbychemicalagents,(5)restricting
accesstoatmosphericoxygenusingphysicalprinciplesor
mechanicaldevices.Thetechniquesmostcommonlyusedto
culturemicroorganismsunderanaerobicconditionsaredivided
into:chemical,biological,physicalandmixedtechniques.
Chemicalmethodsaremainlybasedonremovingoxygenby
meansofareducingagent.Forthispurpose,chemicalcompounds
areplacedinjarsorothervesselsinwhichanaerobiccultures
arecarriedout.ThesecompoundsincludepyrogalolorKOH.
Theculturesalsouseagentssuchasdithiothreitol,L-cysteine
hydrochloride,2-mercaptoethanesulfonate(coenzymeM),sodium
sulphite,sodiumthiosulphate,glutathioneortitanium(III)citrate,
whichcanbeintroduceddirectlyintoliquidorsolidifiedagar
media.However,duetodiferentchemicalandbiologicalproperties
ofthereducingagentsused(e.g.redoxpotential,toxicity),theymay
inhibitthegrowthofcertaingroupsofanaerobes.
Biologicaltechniquesofanaerobicmicroorganismsculturing
aremainlybasedontheFortner’smethod(theso-calledFortner’s
plates).Itisbasedonthecommonculturing(sidebyside)of
anaerobesandaerophilicmicroorganisms.Aftersometime,
aerobicmicroorganisms,usingoxygenduringtheirdevelopment,
createtheconditionsconducivetothegrowthofanaerobes.
Themostfrequentlyusedphysicalandmixed(physicochemical)
methodsofobtaininganaerobicconditionsincludeculturingin
speciallyprepareddevicescalledanaerostats.
Anaerobicconditionsareobtainedinthesevesselsby:
(1)pumpingouttheairusingavacuumpumpandthen
introducingtheanaerobicgasorgasesthroughasystemof
appropriatevalvesand/or(2)usingchemicalmethodstogenerate
ananaerobicatmospherebasedonsimplechemicalreactionsand
metalliccatalysts.Thefollowingaremainlyusedinprocedures
withchemicalagents:sodiumboride,palladiumcatalystandCO
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