Microbial biofloc as source of probiotic bacteria for the culture of Litopenaeus vannamei

• Published in: Aquaculture Vol. 448; pp. 273 - 279
• Main Authors: Ferreira, Gabriela Soltes, Bolívar, Norha Constanza, Pereira, Scheila Anelise, Guertler, Cristhiane, Vieira, Felipe do Nascimento, Mouriño, José Luiz Pedreira, Seiffert, Walter Quadros
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2015; Elsevier Sequoia S.A
• Subjects: Aquaculture; Bacillus; Bacillus cereus; Bacillus licheniformis; Bacillus sp; Bacillus thuringiensis; Biofloc; Decapoda; Health; Litopenaeus vannamei; Microbiology; Pathogens; Probiotic; Probiotics; Shellfish; Shrimp; Vibrio alginolyticus; Probiotic; Bacillus sp; Health; Biofloc; Shrimp
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2015.06.006

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 42days 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 20mm 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<0.05) in the microbiological count of the water on the seventh day of testing, when the total count of Vibrio spp. in water was lower in the groups treated with Bacillus spp. (1×104CFU·mL−1) than in the control group. In the fattening test, supplementation with Bacillus spp. did not affect the performance of shrimp, however, there were no significant differences (p<0.05) in the immunological parameters, Bacillus spp. strains were able to increase the total count of hemocytes, the serum binder content and the total protein in serum, and decrease the hemolymph phenoloxidase (PO) activity. There was also an increase (p<0.05) in the intracellular production of superoxide anion stimulated by laminarin (β-1,3 glucans) and PMA (Phorbol myristate acetate) compared to the baseline. The conclusion is that the Gram-positive bacteria Bacillus spp., isolated from microbial bioflakes, are important for the cultivation and maintenance of the health and growth of L. vannamei, and can be used as probiotics or as biocontrol for water in super-intensive culture systems. 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. •The Bacillus licheniformis was able to inhibit the pathogen V. alginolyticus in vitro.•The use of isolated strains added to the biofloc system decreased the concentration of Vibrio spp. in the water.•Supplementation with probiotic Bacillus spp. in the diet increased the response of immunological parameters in marine shrimp.