Role of Hypermutability in the Evolution of the GenusOenococcus

Publisher Website
Google Scholar
Abstract
Oenococcus oeniis an alcohol-tolerant, acidophilic lactic acid bacterium primarily responsible for malolactic fermentation in wine. A recent comparative genomic analysis ofO. oeniPSU-1 with other sequenced lactic acid bacteria indicates that PSU-1 lacks the mismatch repair (MMR) genesmutSandmutL. Consistent with the lack of MMR, mutation rates forO. oeniPSU-1 and a second oenococcal species,O. kitaharae, were higher than those observed for neighboring taxa,Pediococcus pentosaceusandLeuconostoc mesenteroides. Sequence analysis of therpoBmutations in rifampin-resistant strains from both oenococcal species revealed a high percentage of transition mutations, a result indicative of the lack of MMR. An analysis of common alleles in the two sequencedO. oenistrains, PSU-1 and BAA-1163, also revealed a significantly higher level of transition substitutions than were observed in otherLactobacillalesspecies. These results suggest that the genusOenococcusis hypermutable due to the loss ofmutSandmutL, which occurred with the divergence away from the neighboringLeuconostocbranch. The hypermutable status of the genusOenococcusexplains the observed high level of allelic polymorphism among knownO. oeniisolates and likely contributed to the unique adaptation of this genus to acidic and alcoholic environments.