Kathiravan Velusamy

Publications (6) View all

• Article: Diversity of diazotrophic bacteria in greenwater system of coastal aquaculture

  V. Kathiravan, K.K.Krishnani
  Journal of Environmental and Applied Bioresearch. 01/2012; 1(1):5-11.
• Article: Heterotrophic Nitrifying and Oxygen Tolerant Denitrifying Bacteria from Greenwater System of Coastal Aquaculture.

  Kathiravan Velusamy, Kishore Kumar Krishnani
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  ABSTRACT: 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 (GC-FAME) 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.
  Applied biochemistry and biotechnology 01/2013; · 1.94 Impact Factor
• Article: Diversity of nitrite oxidizers in greenwater system of coastal aquaculture by metagenomic approach targeting NxrB genes

  V.Kathiravan, K.K.Krishnani, I.S. Azad, M. Kailasam, A.G.Ponniah
  Biotechnology An Indian Journal 0974 - 7435. 01/2012; 6(11):359-366.
• Article: Diversity of sulfur-oxidizing bacteria in greenwater system of coastal aquaculture.

  Kishore Kumar Krishnani, V Kathiravan, M Natarajan, M Kailasam, S M Pillai
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  ABSTRACT: Reduced sulfur compounds produced by the metabolism are the one of the major problems in aquaculture. In the present study, herbivorous fishes have been cultured as biomanipulators for secretions of slime, which enhanced the production of greenwater containing beneficial bacteria. The genes encoding soxB which is largely unique to sulfur-oxidizing bacteria (SOB) due to its hydrolytic function has been targeted for examining the diversity of SOB in the green water system of coastal aquaculture. Novel sequences obtained based on the sequencing of metagenomic clone libraries for soxB genes revealed the abundance of SOB in green water system. Phylogenetic tree constructed from aligned amino acid sequences demonstrated that different clusters have only 82-93% match with Roseobacter sp., Phaeobacter sp., Roseovarius sp., Sulfitobacter sp., Ruegeria sp., and Oceanibulbus sp. The level of conservation of the soxB amino acid sequences ranged from 42% to 71%. 16S rRNA gene analyses of enrichment culture from green water system revealed the presence of Pseudoxanthomonas sp., which has 97% similarity with nutritionally fastidious Indian strain of Pseudoxanthomonas mexicana-a sulfur chemolithotrophic gamma-proteobacterium. Our results illustrate the relevance of SOB in the functioning of the green water system of coastal shrimp aquaculture for oxidation of reduced sulfur compounds, which in turn maintain the sulfide concentration well within the prescribed safe levels.
  Applied biochemistry and biotechnology 11/2010; 162(5):1225-37. · 1.94 Impact Factor
• Article: A quantitative method for detecting ammonia-oxidizing bacteria in coastal aquaculture systems

  K.K.Krishnani, V.Kathiravan
  Aquaculture Research 01/2010; 41:1648-1657. · 1.20 Impact Factor