Bright Singh, I S; Rosamma, Philip; Vrinda, Sukumaran; Cini, Achuthan; Rejish Kumar, V J; Valsamma, Joseph(Elsevier, February 10, 2013)
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Abstract:
The addition of commercial nitrifying bacterial products has resulted in significant improvement of
nitrification efficiency in recirculating aquaculture systems (RAS). We developed two nitrifying bacterial
consortia (NBC) from marine and brackish water as start up cultures for immobilizing commercialized
nitrifying bioreactors for RAS. In the present study, the community compositions of the NBC were
analyzed by universal 16S rRNA gene and bacterial amoA gene sequencing and fluorescence in situ
hybridization (FISH). This study demonstrated that both the consortia involved autotrophic nitrifiers,
denitrifiers as well as heterotrophs. Abundant taxa of the brackish water heterotrophic bacterial isolates
were Paenibacillus and Beijerinckia spp. whereas in the marine consortia they were Flavobacterium,
Cytophaga and Gramella species. The bacterial amoA clones were clustered together with high similarity
to Nitrosomonas sp. and uncultured beta Proteobacteria. FISH analysis detected ammonia oxidizers
belonging to b subclass of proteobacteria and Nitrosospira sp. in both the consortia, and Nitrosococcus
mobilis lineage only in the brackish water consortium and the halophilic Nitrosomonas sp. only in the
marine consortium. However, nitrite oxidizers, Nitrobacter sp. and phylum Nitrospira were detected in
both the consortia. The metabolites from nitrifiers might have been used by heterotrophs as carbon and
energy sources making the consortia a stable biofilm.
Description:
International Biodeterioration & Biodegradation 78 (2013) 74e81