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Microbialbiotechnologyinthelaboratoryandinpractce
ortheuseofin-situ/invivocultures,whichbymappingliving
conditionsalmostidenticaltothenaturalonesallowthegrowth
ofanaerobes,causingmanydifcultiesinculturing.Improved
anaerobiccultureproceduresalsoincludethemethodusing
6-wellplatesandanaerobicgaspackagingsystem.Thistechnique
isbasedonaninoculationofaspecificdilutionofthetested
material,mixedpreviouslywithagrowthmediumcontaining
gellangumona6-wellplate,andthenplacingtheplatewiththe
appropriatecatalystsinasealedbagandcreatingananaerobic
atmospherethroughaneedleinsertedintothebag.Thismethod
isparticularlyusefulforthecultureofobligateanaerobes,
includingmethanogensandsulphate-reducingbacteria.
BacteriaofthegenusPropionibacteriumbelongtothe
Acinobacteriaphylum.Theyarecharacterisedbyhigh
heterogeneityintermsofmorphologicalandbiochemicalfeatures
andnutritionalrequirements.Theircellscantakediferentshapes
(pleomorphism)dependingonthegrowthphaseandtheamount
ofoxygenintheenvironment.Theyaremostlycylindrical,butcan
alsotakesphericalorYorV-likeforms.AllPropionibacterium
speciesarenon-sporulating,havenomotionorganellesandbelong
toGram-positivebacteria.Itshouldbenoted,however,thatsome
strains,intheinitialstageofgrowth,maybeGram-variable.
Theyrequireanaerobicconditionsforgrowth,althoughmost
cantoleratelowoxygenconcentrationsintheenvironmentand
thereforebelongtomicroaerophilicbacteria.
ThespeciesbelongingtoPropionibacteriumareconventionally
dividedintotwogroups:theso-called“classical”,alsoknownas
lactic,isolatedfromcheeseandotherdairyproducts,butalsofrom
thesoilornaturalproductssuchasorangejuice;andthe“skin”
bacteriabelongingtotheexo-andendogenousbacterialmicrobiota
thatinhabittheskinandmucousmembranesofthemouthor
digestivetract.Thereare13speciesofthisgenus,ofwhich6belong
tothe“classical”bacteria(P.thoenii,P.freudenreichii,P.jensenii,
P.cyclohexanicum,P.microaerophilumandP.acidipropionici),
and7tothe“skin”bacteria(P.acnes,P.granulosum,P.australiens,
P.propionicus,P.humerusii,P.acidifaciensandP.avidum).
Duetoitsmanybeneficialclassicalproperties,Propionibacterium
bacteriaareusedinmanyindustries.Thegreatestpotential
isfoundinthefoodindustryandinthegeneralprotectionof
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