Quorum quenching potentials of probiotic Enterococcus durans Lab38 against methicillin resistant Staphylococcus aureus

Abstract

Objective: The focus of this study was to explore the nuance strategy to combat the virulence factors of the pathogens by probiotic Enterococcus durans LAB38. Methods: Probiotic attributes was determined by bile salt tolerance (0.5%) and Artemia gnotobiotic assay. Quorum sensing (QS) inhibitory activity of the supernatant and ethyl acetate (EA) extract of LAB38 was evaluated using the indicator strains, includes Chromobacterium violaceum CV026 (mini-Tn5 mutant of ATCC 31532), methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PA). Reporter strains, Vibrio harveyi BB170 (luxN mutant), BB886 (luxP mutant) and Escherichia coli pSB401 (pACYC184-derived) were used for bioluminescence-based target specificity analysis. Gas chromatography-mass spectrometry (GC-MS) analysis of EA extract was performed using standard protocol. Results: LAB38 has shown bile salt tolerance and positive probiotic effect toward Artemia salina. In addition, 100 µg/ml EA extract has significantly reduced the violacein production (37±1.4%) in CV026, biofilm formation in MRSA (94±0.9 %) and PA (22±0.08%). Further, 200 µg/ml of EA extract has shown inhibition against both autoinducer-1 (AI-1) and AI-2 mediated QS system. Bioluminescence inhibition is directly proportional to the time of exposure. GC-MS result revealed that bromine, sulfur containing molecule and azulene derivative were found in the EA extract. Conclusion: This is the first report on probiotic E. durans for quorum quenching activity. Hence, the bacterium could be used for future therapeutics application.