Lactobacillus pentosus genes involved in olive brine stress response

Background: Olives can be consumed only after a fermentation process driven by lactic acid bacteria (LAB) and yeasts. Only few adapted strains of LAB are able to grow and ferment table olives. In fact olive brine represents a stressful environment due to high NaCl concentration, presence of phenolic compounds known as antimicrobials, and low availability of nutrients. Objectives and methods: Lactobacillus pentosus C11 is a particularly resistant strain isolated from naturally fermented table olives. In order to identify the mechanisms by which this strain is able to tolerate olive brine stress conditions, a random transposition mutagenesis using the Pjunc-TpaseIS1223-based system was carried out. A library of 6000 mutants was generated and screened for the ability to grow in a brine based medium. Results and conclusion: Five transposition mutants impaired in growth on brine based medium were identified. The genotypic analysis allowed the identification of 5 genes involved in brine stress response of L. pentosus C11.