To identify novel actors responsible for the marked adaptation of the Oenococcus oeni species to its environment. Genomic surveillance of the available genome sequences from O. oeni indicated the presence of a small ORF, encoding a protein named Dps(A). The cloned gene complemented the dps(-) mutant of Escherichia coli and conferred resistance to hydrogen peroxide, wine, and metals. The dps(A) gene was flanked by IS-related elements. The entire region was characterized by an anomalously high GC content compared to those reported for oenococcal genomes. The dps(A) gene was present in 15 of the 38 tested isolates. Positive strains originated from different geographical areas and sources. No change in tolerance to wine or to oxidative stress was observed between O. oeni strains harbouring dps(A) and those not harbouring this gene. Some O. oeni have acquired a functional homologue to the dps gene from E. coli as part of a mobile element. Dps(A) probably increases the bacterial fitness in response to environmental challenges. However, the physiological condition under which it adds a selective advantage to O. oeni during winemaking remains to be found.