The genus Weissella: taxonomy, ecology and biotechnological potential.

BacteriaassignedtothegenusWeissellaareGram-positive,catalase-negative,non-endosporeformingcellswithcoccoidorrod-shapedmorphology(Collinsetal.,1993;Björkrothetal.,2009,2014)andbelongtothegroupofbacteriagenerallyknownaslacticacidbacteria.Phylogenetically,theWeissellabelongtotheFirmicutes,classBacilli,orderLactobacillalesandfamilyLeuconostocaceae(Collinsetal.,1993).Theyareobligatelyheterofermentative,producingCO2fromcarbohydratemetabolismwitheitherD(-)-,oramixtureofD(-)-andL(+)-lacticacidandaceticacidasmajorendproductsfromsugarmetabolism.Todate,thereare19validlydescribedWeissellaspeciesknown.Weissellaspp.havebeenisolatedfromandoccurinawiderangeofhabitats,e.g.,ontheskinandinthemilkandfecesofanimals,fromsaliva,breastmilk,fecesandvaginaofhumans,fromplantsandvegetables,aswellasfromavarietyoffermentedfoodssuchasEuropeansourdoughsandAsianandAfricantraditionalfermentedfoods.Thus,apartfromaperceivedtechnicalroleofcertainWeissellaspeciesinvolvedinsuchtraditionalfermentations,specificWeissellastrainsarealsoreceivingattentionaspotentialprobiotics,andstraindevelopmentofparticularlyW.cibariastrainsisreceivingattentionbecauseoftheirhighprobioticpotentialforcontrollingperiodontaldisease.Moreover,W.confusaandW.cibariastrainsareknowntoproducecopiusamountsofnovel,non-digestibleoligosaccharidesandextracellularpolysaccharides,mainlydextran.Thesepolymersarereceivingincreasedattentionfortheirpotentialapplicationasprebioticsandforawiderangeofindustrialapplications,predominantlyforbakeriesandfortheproductionofcereal-basedfermentedfunctionalbeverages.Onthedetrimentalside,strainsofcertainWeissellaspecies,e.g.,ofW.viridescens,W.cibariaandW.confusa,areknownasopportunisticpathogensinvolvedinhumaninfectionswhilestrainsofW.cetihavebeenrecentlyrecongnizedasetiologicalagentof"weissellosis,"whichisadiseaseaffectingfarmedrainbowtrouts.Bacteriabelongingtothisspeciesthusareimportantbothfromatechnological,aswellasfromamedicalpointofview,andbothaspectsshouldbetakenintoaccountinanyenvisagedbiotechnologicalapplications.