Presumptive probiotic isolated from Oncorhynchus mykiss (Walbaum, 1792), cultivated in Mexico

Document Type: Primary Research paper

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Abstract

The intestinal microbial community of fish is determining by biotic and abiotic factors, and depending on the niche they occupy, we can distinguish between transient and permanent microorganisms. The last ones, are important for aquaculture, due to its probiotic potential. Three adult of Oncorhynchusmykiss were used to extract their intestine to isolate the bacteria present and tested to determine probiotic ability: resistance to acidic pH and bile, adhesion, hemolytic activity, antibiotic susceptibility, and in vitro antagonism. Bacteria groups were identified by sequencing the 16S rRNA. Fourteen bacterial strains were obtained, of which the strains Bacillus pumilus, Shewanella xiamenensis, Bacillus sp. and Bacillus methylotrophicus were able to grow at acidic pH in the presence of bile and only S. xiamenensis showed α-hemolytic activity. B. pumilus and Bacillus sp. had better adhesion and antagonism in vitro. We can conclude that B. pumilus and Bacillus sp. presented potential probiotics in vitro and is recommendable to evaluate them in rainbow trout to determine what benefits they can offer to this fish.

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