New insights into the molecular effects and probiotic properties of Lactobacillus pentosus pre-adapted to edible oils

In this study, the survival and growth of seven probiotic Lactobacillus pentosus strains isolated from Alorefia green table olives in the presence of vegetable-based edible oils (i.e., sunflower, olive, linseed, soy, corn, almond and argan) and mint essential oil were determined for the first time. Slight decreases in bacterial viability were observed depending on the strain and oil exposure, mainly mint essential oil. However, pre-adaptating the strains to the corresponding oils significantly increased their cell viabilities. As such, this study examined whether pre-adaptating probiotic L pentosus strains with oils will constitute a new strategy to increase stress resistance, e.g., acids (pH 1.5) or bile (up to 3.6%) in food production and/or during digestion, and improve functional probiotic properties. Improvements in stress resistance (acidic and bile conditions) were noticed in some pre-adapted strains with oils; further, pre-adaptations with olive, argan, sunflower and linseed oils induced gene expression (e.g., fus, rpsL, pgm, groEL, enol and prep) for moonlighting proteins involved in several stress responses and other functions. As such, pre-adaptation with vegetable edible oils may represent a novel approach for manufacturing probiotic products by improving the stability of bacteria during industrial processes that would otherwise reduce their viability and functionality.