Proteomic analysis of Lactobacillus pentosus for the identification of potential markers involved in acid resistance and their influence on other probiotic features

Acidity often prevents the undesirable microbial colonization both in fermented foods and under gastric conditions. Thus, the acid resistance of Lactobacillus pentosus strains used as starter cultures and/or probiotics requires further understanding. This was investigated by means of comparative proteomic approach using three strains representing the phenotypes: resistant (AP2-15), intermediate (AP2-18) and sensitive (LP-1) to acidic conditions. Proteomic analysis of constitutive phenotypes revealed that the intrinsic resistance of L. pentosus is associated with the over-production of three principal proteins: 2,3-bisphosphoglycerate-dependent phosphoglycerate mutase 2 (PGAM-d), elongation factor G and 50S ribosomal protein L10, and additionally on ATP synthase subunit beta and chaperone protein DnaK; they are associated with metabolic pathways of proteins and carbohydrates, energy production and stress responses. Suggested protein biomarkers for acid resistance in L. pentosus include elongation factor G and PGAM-d, both being abundantly found in the constitutive proteome of the resistant phenotype under standard and acidic conditions. Furthermore, L. pentosus strains pre-exposed to acids displayed enhanced probiotic function such as auto-aggregation ability via surface proteins. We conclude that pre-exposure of probiotic L. pentosus strains to acid may strategically enhance their performance as starter cultures and probiotics.