Presence of Oenococcus oeni and other lactic acid bacteria in grapes and wines from Priorat (Catalonia, Spain)

- Autochthonous lactic acid bacteria from vineyards and wines of Priorat region were analysed.
- Oenococcus oeni was isolated from several samples of grape berries.
- A great diversity of O. oeni strains from Priorat wines was observed.
- High-throughput sequencing confirmed the presence of Oenococcus in grapes.

Oenococcus oeni, the lactic acid bacterium (LAB) mainly responsible for malolactic fermentation, has been repeatedly isolated from wines, but hardly ever from grapes. In this study, a large survey of autochthonous LAB from the Catalan wine region of Priorat was made. A total of 761 LAB isolates, 254 from Grenache and Carignan grape berries and 507 from wines, were identified and typed. Around 70% of the isolates were O. oeni, mostly from wines, but remarkably, 53 of them were isolated from grapes. A minimum spanning tree of O. oeni strains constructed from the multilocus variable number tandem repeat analysis showed considerable phylogenetic diversity. Other non-Oenococcus species were also identified and typed, Lactobacillus plantarum being predominant in grapes. Other LAB isolates were Pediococcus pentosaceus, Fructobacillus tropaeoli, L. mali, L. lindneri and L. sanfranciscensis. High-throughput sequencing (HTS) analysis was also carried out with grape samples, and Oenococcus and Lactobacillus were detected in significant quantities, which corroborates the culturing results from the same samples.