Antibacterial activity, antibiotic susceptibility and probiotic use of lactic acid bacteria (LAB) in Persian sturgeon (Acipenser persicus)

Growth behavior of five lactic acid bacteria previously isolated from Persian sturgeon (Acipenser persicus), were evaluated at different pH, temperature and salt concentrations. Also, antibacterial activity of extracellular products (ECPs) of this LAB were assessed to Aeromonas hydrophila. Further, their antibiotic susceptibility was determined with some commonly used antibiotics in aquaculture. In an in vivo work the effect of Lactococcus lactis as the supplementary diet was evaluated on growth performance of Persian sturgeon for a period of 56 days. Strong growth of all LAB were seen at 20 and 30?C, as well as 40 and 80 g L-1 NaCl. The LAB ECPs exhibited varied results of antagonism to the A. hydrophila with maximum activity observed at temperature between 25 and 30?C. Also, the higher antagonistic activity was observed for ECPs of W. cibaria, P. pentosaceus, and L. lactis at pH 9. Both W. cibaria and E. faecalis were resistance to oxytetracycline, erythromycin, trimethoprim sulfamethoxazol, enrofloxacin, florfenicol, and flumequine, while L. lactis was sensitive to oxytetracycline, erythromycin, enrofloxacin, florfenicol. These results showed that use of L. lactis can act as a positive probiotic in Persian sturgeon feed via improvement of fish growth performance, feed efficiency and fish health.