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The objective of this study was to isolate and identify bacteria of the genus Bacillus sp. from a super-intensive culture system with Litopenaeus vannamei microbial flakes, and evaluate their potential of affecting the water quality, performance and immunological parameters when added to the water and diet. Bacillus spp. isolates were evaluated in vitro for the ability to inhibit pathogens, antagonistic activity. After selection, Bacillus spp. was added to the water to assess the influence in the formation and maintenance of microbial flakes in post-larvae culture. In order to verify the performance and hemato-immunological parameters of L. vannamei for 42 days of culture, they were incorporated in formulated diets. Four bacteria were isolated from the microbial flakes super-intensive system: Bacillus thuringiensis CPQBA 571-12 DRM 06 (> 99%), Bacillus licheniformis CPQBA 571-12 DRM 07 (> 99%), B. licheniformis CPQBA 571-12 DRM 08 (> 99%) and Bacillus cereus CPQBA 571-12 DRM 09 (> 99%). B. licheniformis CPQBA 571-12 DRM 07 was the only isolate that showed in vitro inhibitory characteristics against the pathogen Vibrio alginolyticus (BCCM 2068) with a 20 mm diameter inhibition zone and the isolates did not show any antagonistic activity. For the test of formation and maintenance of microbial aggregates generated in the post-larvae culture super-intensive system, a significant difference was observed (p Statement of relevance Bacillus spp. were isolated from biofloc system water and can be supplemented in shrimp (L. vannamei) feed to increase immunocompetence and used as biocontrol for Vibrio spp. in water. |
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