R. Vinothkumar, V. S. Bharti, A. Vennila, H. Sanath Kumar and P.K. Pandey
Abstract
Isolation and identification of indigenous bacteria are essential for bio-remediating the nitrogenous wastes in aquaculture systems. Nitrite is one of the critical issues inherent to the aquaculture systems due to its toxicity, and hence it is rightly called as “invisible killer”. In this study, the heterotrophic nitrifying denitrifying bacteria were isolated and characterized from shrimp ponds of Maharashtra. The samples were enriched and bacteria were isolated using Mineral salt media. For molecular identification of the bacteria, the 16S rDNA gene was PCR amplified using universal primers, sequenced and analyzed by BLAST comparison. 15 isolates were identified and selected for nitrate and nitrite removal assay. The nitrate removal activity ranged from 3.012 ± 0.072 to 17.513 ± 0.010 mg of NO3-N/l in 24h. The nitrite removal activity ranged from 9.385 ± 0.069 to 18.345 ± 0.012 mg NO2-N/l in 24h. In the present study, the isolates Microbacterium esteraromaticum (M6) and Ochrobactrum intermedium (M13) significantly removed nitrate-N and nitrite-N respectively. The isolated species have the potentials to be used as bioremediation to overcome the toxicity of nitrogenous compounds in aquaculture systems.