Biodiversity and geographical origin of Oenococcus oeni strains

Abstract: Oenococcus oeni is usually the unique bacterial species responsible for malolactic fermentation (MLF) in wine and it is known to show a certain phenotypic and genotypic diversity at strain level. In order to evaluate whether such biodiversity could be related to the geographical origin of O. oeni strains, 84 bacterial isolates from Italian wines of different oenological areas were characterized both phenotypically, by determining fatty acid composition (FAME) and metabolic compounds at the end of MLF, and genotypically, by Pulsed Field Gel Electrophoresis (PFGE) after ApaI restriction digestion of genomic DNA. Cluster and principal component analysis of phenotypic data showed a high biodiversity among the different strains, but no correlation between phenotypic groups and the origin of the strains was evidenced. Conversely, on the basis of ApaI PFGE restriction patterns, the 84 isolates were grouped into five different clusters at 70% similarity, and a sort of relationship between genotypic groups and the wine-producing areas was found. When phenotypic clusters obtained by numerical analysis of FAME profiles were combined to genotypic clusters, the 84 O. oeni isolates grouped into eight combined profiles and the relationship between the geographical origin of the isolates and their combined profile became more evident. Hence, the combined profiles appear as a useful tool to differentiate and thus to recognize O. oeni strains originating from a specific wine-producing area. The evidence that the intraspecific biodiversity of O. oeni can be related to the geographical origin of the strains suggests to select and to use specific malolactic starter cultures to induce malolactic fermentation in typical wines.