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  300 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  300 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.