Probiotic potential and anti-quorum sensing activity of Enterococcus faecalis and Lactobacillus kunkeei isolates from Apis mellifera

This study aimed to investigate the antimicrobial, anti-quorum sensing activity and potential probiotic properties of Lactobacillus kunkeei and Enterococcus faecalis 1 and 2 isolates from Apis mellifera gut. The antimicrobial and anti-QS activity of isolates were determined by the broth microdilution method and the Chromobacterium violaceum biosensor strain, respectively. The probiotic potential was evaluated according to EFSA standards. The organic acid content of culture supernatants of isolates was determined quantitatively by a HPLC method. Results showed that isolates were found to be resistant to gentamicin, streptomycin, erythromycin, and clindamycin. Also, isolates were found gamma haemolytic and resistant to acidic and enzymatic environmental conditions. E. faecalis isolates showed antimicrobial activity against Escherichia coli ATCC 25922, E. faecalis ATCC 29212, and Pseudomonas aeruginosa ATCC 27853. Anti-quorum sensing activity of the culture supernatants of all isolates was found as a violacein pigment inhibition against Chromobacterium violaceum biosensor strain. The concentrations of lactic acid, acetic acid and butyric acid produced by isolates were found as 1.7 - 7.5 g/L, 0.94 - 2.20 g/L and 0.22 - 0.38 g/L, respectively.