Comparative proteomic analysis of a potentially probiotic Lactobacillus pentosus MP-10 for the identification of key proteins involved in antibiotic resistance and biocide tolerance

• The potential probiotic multi-drug resistant Lactobacillus pentosus MP-10 is regarded as safe.
• Different proteomic profiles in antibiotic and biocide adapted Lb. pentosus were shown.
• Alteration of Lb. pentosus MP-10 physiology after induction with antibiotics and biocides.
• Adapted Lb. pentosus to antimicrobials could be a good alternative to improve its robustness.

Probiotic bacterial cultures require resistance mechanisms to avoid stress-related responses under challenging environmental conditions; however, understanding these traits is required to discern their utility in fermentative food preparations, versus clinical and agricultural risk. Here, we compared the proteomic responses of Lactobacillus pentosus MP-10, a potentially probiotic lactic acid bacteria isolated from brines of naturally fermented Aloreña green table olives, exposed to sub-lethal concentrations of antibiotics (amoxicillin, chloramphenicol and tetracycline) and biocides (benzalkonium chloride and triclosan). Several genes became differentially expressed depending on antimicrobial exposure, such as the up-regulation of protein synthesis, and the down-regulation of carbohydrate metabolism and energy production. The antimicrobials appeared to have altered Lb. pentosus MP-10 physiology to achieve a gain of cellular energy for survival. For example, biocide-adapted Lb. pentosus MP-10 exhibited a down-regulated phosphocarrier protein HPr and an unexpressed oxidoreductase. However, protein synthesis was over-expressed in antibiotic- and biocide-adapted cells (ribosomal proteins and glutamyl-tRNA synthetase), possibly to compensate for damaged proteins targeted by antimicrobials. Furthermore, stress proteins, such as NADH peroxidase (Npx) and a small heat shock protein, were only over-expressed in antibiotic-adapted Lb. pentosus MP-10. Results showed that adaptation to sub-lethal concentrations of antimicrobials could be a good way to achieve desirable robustness of the probiotic Lb. pentosus MP-10 to various environmental and gastrointestinal conditions (e.g., acid and bile stresses).