Microbial biodiversity of Sardinian oleic ecosystems

摘要

AbstractThe olives are rich in microorganisms that, during the extraction process may persist in the oils and can influence their physicochemical and sensory characteristics. In this work, and for the first time, we isolated and identified microbial species, yeast and bacteria, present during the production process in four Sardinian (Italy) oleic ecosystems. Among these varieties, we found thatNera di Gonnoswas associated to the highest microbial biodiversity, which was followed byBosana, Nocellara del BeliceandSemidana.Among the different microbial species isolated, some are specific of olive ecological niches, such asCryptococcusspp andSerratiaspp; and others to olive oils such asCandidaspp andSaccharomyces. Some other species identified in this work were not found before in oleic ecosystems. The enzymatic analyses of yeast and bacteria showed that they have good β-glucosidase activity and yeast also showed good β-glucanase activity. The majority of bacteria presented lipolytic and catalase activities while in yeast were species-specific. Interestingly, yeast and bacteria isolates presented a high resistance to bile acid, and about 65% of the yeast were able to resist at pH 2.5 for 2 h. Finally, bacteria showed no biofilm activity compared to yeast.Highlights•Confirmed the strong selective pressure on bacteria and yeast exerted by mono-varietal olive oils.•Yeast and bacteria showed good β-glucosidase activity.•Bacteria showed the highest lipolytic activity.•Ninety percent of Isolates presented a high resistance to bile acid.•Forty percent of the yeast were able to form a biofilm.