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Kathiravan V.,Central Institute of Brackishwater Aquaculture | Krishnani K.K.,National School of Management
World Journal of Microbiology and Biotechnology | Year: 2014

In the present work, novel heterotrophic nitrifying and aerobic denitrifying bacteria have been isolated from greenwater system of coastal aquaculture. Based on the 16S rRNA gene, FAME analysis and biochemical test, the isolates have been identified as Pseudomonas aeruginosa and Achromobacter sp. These have been named as P. aeruginosa strain DBT1BNH3 and Achromobacter sp. strain DBTN3. Denitrifying functional genes such as nitrite reductase (nirS), nitric oxide reductase (qnorB) and nitrous oxide reductase (nosZ) genes have been identified. These strains found to have a 27 kb plasmid coding for nirS and nosZ. The possibility of horizontal transfer of plasmid among Pseudomonadaceae and Alcaligenaceae families in coastal aquaculture has been explored. Further, we have studied combined nitrification and oxygen tolerant denitrification potential in the same isolates. © 2013 Springer Science+Business Media Dordrecht.

Velusamy K.,Central Institute of Brackishwater Aquaculture | Krishnani K.K.,National School of Management
Applied Biochemistry and Biotechnology | Year: 2013

In this work, herbivorous fish Mugil cephalus has been cultured to secrete protein rich green slime, which helps nitrifying and oxygen tolerant denitrifying bacteria to grow and colonize. Four strains representing Alcaligenaceae family have been isolated from greenwater system and characterized using biochemical test, fatty acid methyl ester (GCFAME) analysis, 16S rRNA and functional gene approaches. They were tested for an ability to nitrify ammonia and nitrite aerobically. Two strains showed notable nitrification activity, when grown in a mineral salts medium containing ammonium sulfate and potassium nitrite. Functional gene analysis confirmed the presence of nitrous oxide reductase (nosZ) gene showing that they have an oxygen-tolerant denitrification system. It has been proposed that Alcaligenes faecalis strains heterotrophically nitrify ammonia into nitrite via formation of hydroxyl amine, which is oxidized to nitrous oxide using oxygen or nitrite as electron acceptor. These results provide a possible advantage of having nitrification and denitrification capabilities in the same organism, which plays an important role in biological wastewater system. © Springer Science+Business Media New York 2013.

Satellite data of Landsat TM, IRS 1B LISS II, IRS 1C LISS III and IRS 1D LISS III were used to monitor aquaculture development and its spatial distribution in Cuddalore District, south-east coast of India. Analysis of satellite images using image processing software ERDAS Imagine 9.0 and Geographic Information System (GIS) software Arc GIS 9.0 indicated that the area under aquaculture was 6.91 ha in 1987, gradually increasing to 67.71 ha in 1994, and reaching a maximum of 380.19 ha in 1998. There was a little shrimp culture development (6.14 ha) from 1998 to 2005 because of risk of White Spot Syndrome Virus (WSSV), epizootics and constraints related to social and environmental concerns raised against shrimp farming. Shrimp farms initially started in the marsh areas close to creeks and then moved inland towards agricultural and fallow lands. Farms developed in clusters along the creeks without affecting mangrove reserve forests between 1988 and 2005 and about 177.02 ha agriculture land including 234.25 ha fallow lands were converted for aquaculture farming. Shrimp culture was abandoned in 109.47 ha and 15.13 ha of agricultural land previously converted to aquaculture farms, was reconverted for agriculture. The present study shows that remote sensing data and GIS are useful tools in assessing and monitoring the development of aquaculture for larger areas and suggests that national level planning using multi-spectral satellite data can be used to assess the existing land use and the potential for sustainable use of coastal resources.

Panigrahi A.,Central Institute of Brackishwater Aquaculture
Journal of Applied Aquaculture | Year: 2012

An epidemiological investigation was done in brackish water culture systems in three coastal districts of West Bengal. A total of 198 farms were randomly surveyed with a structured questionnaire. The data showed that there was a significant difference in outbreak of white spot disease (WSD) (p < 0.01), shell-associated problems (p < 0.01), and gill-associated problems (p < 0.05) among the culture systems. Among all systems, stunted and uneven growth and white fecal disease (only in shrimp monoculture) were the dominant emerging disorders. WSD remained the most prevalent disease. Some farms tested (polymerase chain reaction [PCR]) positive for WSD, but the animals were apparently healthy. Chlorination, use of PCR screening, application of immunostimulants, and strict bio-security measures play major roles in containing disease outbreaks. © 2012 Copyright Taylor and Francis Group, LLC.

Krishnani K.K.,Central Institute of Brackishwater Aquaculture
Aquaculture | Year: 2010

Nucleic acid methods based on sequencing of clone libraries provide sequence and the phylogenetic information of an individual clone. In the present study, ammonia monooxygenase (amoA), nitrite-oxido-reductase(norB), nitrite reductase (nirS) and nitrous oxide reductase (nosZ) genes are chosen to detect nitrifiers and denitrifiers in coastal aquaculture using gene-specific primers. The abundance of these functional genes revealed the presence of nitrifying and denitrifying organisms in coastal aquaculture. Nitrifying and denitrifying communities were analyzed by parallel DNA extractions and clone library construction for amoA, norB, nirS and nosZ obtained from coastal aquaculture soil. Amino acids in parts of the amoA, norB, nirS and nosZ encoded proteins were aligned to know conserved amino acid residues. The amoA genes exhibited 81-82% identity to Nitrosomonas europaea, Nitrosococcus mobilis and Nitrosomonas eutropha which were also similar to particulate methane monooxygenase (pmoA) gene sequences. The norB genes are closely affiliated with Nitrobacter winogradskyi and other uncultured beta-proteobacteria. The nosZ genes exhibited 78-82% identity with Marinobacter sp. and other uncultured denitrifying gamma-proteobacteria. The present study could be useful for making bioremediation strategy for nitrogenous metabolites and understanding of nitrogen fluxes generated through these two functional groups in coastal shrimp aquaculture. © 2010 Elsevier B.V. All rights reserved.

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