The Commercial Perspective of Probiotics and Bioremediating Components in Aquaculture Pond Management: A Case Study

Abstract

Four bacterial strains, i.e., FB5, FB7, FB9, and FB12, from the GI tract of Penaeus vannamei and the strain FB19 were isolated from different P. vannamei culture ponds, and their probiotic potentiality and bioremediating capability were studied. Through ribosomal DNA sequence profiling, strains FB5, FB7, FB9, FB12, and FB19 were identified as Bacillus subtilis, Bacillus circulans, Bacillus subtilis, Bacillus licheniformis, and Pseudomonas sp., respectively. The isolated bacterial strains are able to produce different enzymes like amylase, protease, phytases, and beta-galactosidase that are very essential for shrimp growth and cleanup of the pond bottom condition. All the Bacillus strains showed antimicrobial activity against shrimp pathogen like V. harveyi MTCC 7954 and V. vulnificus MTCC 1145, but B. subtilis FB5 highest zones of inhibition against V. harveyi MTCC 7954 and V. vulnificus MTCC 1145 were 15.3 ± 1.11 mm and 16.1 ± 1.34 mm, respectively. The serum bactericidal activities of nonspecific immunity of shrimps were also measured. Heterotrophic nitrifying and aerobic denitrifying B. subtilis FB5 has the ability to remove${\mathrm{NH}}_4^{+}-\mathrm{N}$, ${\mathrm{NO}}_3^{-}-\mathrm{N}$, and ${\mathrm{NO}}_2^{-}-\mathrm{N}$ at the rate of 76.27, 77.69, and 64.51%, respectively, in synthetic media, whereas aerobic denitrifying Pseudomonas sp. FB19 has the ability to remove 87.14% ${\mathrm{NO}}_2^{-}-\mathrm{N}$in synthetic medium. The bacterial consortium was applied in P. vannamei culture pond, and removal of${\mathrm{NH}}_4^{+}-\mathrm{N}$, ${\mathrm{NO}}_3^{-}-\mathrm{N}$, and ${\mathrm{NO}}_2^{-}-\mathrm{N}$ was also recorded at 86.41, 93.94, and 98.30%, respectively. The results attested that all these Bacillus strains were potential probiotics for P. vannamei and the removal efficiency of toxic nitrogenous pollutants. It was clearly established that this consortium has bioremediating potentiality for sustainable shrimp culture.