Characterization of two potent probiotic strains: Bacillus sp. R2 and Planococcus sp. R11 isolated from the g astrointestinal tract of sea bream (Sparus aurata)

Document Type : Original Article

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Abstract

Probiotics are beneficial microorganisms administrated in aquacultures to control pathogens and enhance feed utilization, survival, and growth rate of farmed fish. This study aimed to get the probiotic bacteria from the gastrointestinal tract which had protease, amylase and lipase activities to improve growth performance of sea bream (Sparus aurata). The most potent selected isolates were identified- using biochemical and molecular sequencing of 16s rRNA gene method- as Bacillus sp. R2 and Planococcus sp. R11 and were characterized to ensure their safety and efficiency. The two bacterial strains were characterized as potential probiotic for hemolytic activity, antibiotic susceptibility, growth pattern, antagonistic activity against fish pathogens, cell surface hydrophobicity and tolerance to acidity and alkalinity. The two strains showed antagonism against the fish pathogen Vibrio alginolyticus isolated from a fish rearing tank. This is the first time to report the probiotic property of genus Planococcus.

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