In vitro screening of potential probiotic lactic acid bacteria isolated from intestinal contents and gills of Nile tilapia
2020
Prachom, N. | Rumjuankiat, K. | Sanguankiat, A. | Boonyoung, S. | Pilasombut, K.
The potential probiotic lactic acid bacteria (LAB) were isolated from intestinal contents and gills of Nile tilapia (Oreochromis niloticus). Those properties included antagonistic activity against pathogenic bacteria, tolerance to pH, NaCl, fresh bile from Nile tilapia. Moreover, drug resistance profiles were examined. A total of forty isolates were collected. LAB isolated from the intestinal contents showed inhibitory activity against Bacillus coagulans TISTR1447, Pseudomonas fluorescens TISTR358 and Salmonella Typhimurium TISTR292, whereas those from the gills revealed only antagonistic activity against Bacillus coagulans TISTR1447, S. Typhimurium TISTR292 and Escherichia coli TISTR780. Isolates LI10 and LG5 were selected for further evaluation of probiotic properties. Both isolates could grow in pH 4–10, NaCl concentration up to 10% and fresh bile concentration up to 10%. These isolates were resistant to cefovecin, marbofloxacin, clindamycin and trimethoprim/sulfamethoxazole, meanwhile they were susceptible to benzylpenicillin, amoxicillin/clavulanic acid, vancomycin, tetracycline, nitrofurantoin and chloramphenicol. In addition, both isolates were identified by Matrix-assisted lazer desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) as Enterococcus feacalis. Therefore, these two isolates could potentially be used as probiotics.
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