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Journal of Biological Sciences
  Year: 2013 | Volume: 13 | Issue: 8 | Page No.: 691-700
DOI: 10.3923/jbs.2013.691.700
Evaluation of Phytase-producing Ability by a Fish Gut Bacterium, Bacillus subtilis subsp. subtilis
Paramita Das and Koushik Ghosh

Phytases produced by the symbiotic bacteria might increase the availability of phosphorus and other nutrients in farmed animals. Unlike terrestrial animals, phytase-producing fish gut bacteria are insufficiently studied. The present study was intended to evaluate phytase-producing gut bacteria in 6 freshwater carps, to identify the most promising one by 16SrDNA and to optimize phytase production by the strain. Homogenates of proximal (PI) and distal (DI) intestinal segments were spread onto Modified Phytase Screening Media (MPSM) plates to enumerate phytase-producing microbiota. Data were presented as Log Viable Counts g-1 intestine (LVC). Phytase producing microbiota was highest in the DI region of Cirrhinus mrigala (LVC = 3.85) followed by the DI region of Labeo rohita (LVC = 3.35). Out of 73 phytase-producing isolates, 14 primarily selected isolates detected through qualitative assay were further screened by quantitative assay using MPSM broth. The strain CM7 isolated from DI of C. mrigala showed highest phytase activity (2.31±0.01 U mL-1) followed by the strain LR2 (2.21±0.01 U mL-1) isolated from DI of L. rohita. Nucleotide homology analysis revealed that the isolate CM7 was similar to Bacillus subtilis subsp. subtilis (Accession no. JX292128). Highest phytase activity by the isolate in submerged culture was recorded as 2.61±0.04 U mL-1 under optimized conditions (pH 7, 35°C, 2.5% inoculum, 4% NaCl, 1% starch, 2% ammonium sulphate, 6 days incubation). Phytase-producing ability of the fish gut bacteria detected in the present study might expand the scope of their use to improve nutrient utilization in fish or other animals.
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How to cite this article:

Paramita Das and Koushik Ghosh, 2013. Evaluation of Phytase-producing Ability by a Fish Gut Bacterium, Bacillus subtilis subsp. subtilis. Journal of Biological Sciences, 13: 691-700.

DOI: 10.3923/jbs.2013.691.700








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