Molecular biological characterization and biostimulation of ammonia-oxidizing bacteria in brackishwater aquaculture

Abstract

In the present study, molecular methods based on sequencing of clone libraries have been used to provide sequence and the phylogenetic information of ammonia oxidizing bacteria (AOB). Ammonia monooxygenase (amoA) gene, which catalyzed the oxidation of ammonia to hydroxyl amine in the initial rate-determining step of nitrification was targeted for detection and characterization of AOB using gene-specific primers. The amoA genes obtained through the clone library construction are closely affiliated with Nitrosomonas sp. and other uncultured beta proteobacteria. The levels of nucleotide similarity and amino acid similarity ranged from 85–99% and 83–88%, respectively. The level of conservation of the amino acid sequences is 73%. The use of a matrix prepared from abundantly available lignocellulosic agrowaste-bagasse has successfully been demonstrated for biostimulation of AOB in aquaculture environment by supplementing nutritional requirement facilitating the biofilm mode of growth of the autotrophic consortia. Present study is useful in predictability and reliability of the treatment of ammonia in brackishwater aquaculture.

Keywords:

• Ammonia-oxidizing bacteria
• ammonia monooxygenase
• bagasse
• biostimulation
• brackishwater aquaculture

Acknowledgments

The authors are grateful to Dr. A.G. Ponniah, Director, Central Institute of Brackishwater Aquaculture, Chennai and Dr. Mathew Abraham and Dr. P. Ravichandran, former Directors, for providing facilities to carry out this work.