Journal of Environmental Biology

Characterization of a novel heterotrophic nitrifying and aerobically denitrifying bacterium, Halomonas sp. Z8, as a potential bioagent for wastewater treatment

Z. Huang¹, Y. Jiang¹, X. Song¹ and E. Hallerman²* 

¹Department of Fisheries, Ocean University of China, Qingdao-266 003, PR China

²Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, VA-24061, USA

*Corresponding Author Email : ehallerm@vt.edu

Paper received: 01.03.2019                                               Revised received: 05.06.2019                                         Accepted: 03.10.2019

Abstract

Aim: The aim of the present study was to identify and characterize the functions of key microbes mediating nitrification.

Methodology: After sampling the biofilm from a submerged biofilter in a marine aquaculture system, selective media were used to isolate microbial strains involved in nitrification. Isolates were identified using physiological and biochemical assays and sequencing of 16S rRNA gene. Nitrogen removal under different conditions was characterized. Nitrogen removal pathway was characterized by a ¹⁵N tracer experiment. Representation of key microbes in the biolfim was characterized by metagenomics analysis.    

Results: Single-factor tests showed that Halomonas sp. strain Z8 exhibited good heterotrophic nitrification and aerobic denitrification abilities, with maximum NH₄⁺-N, NO₂^--N and No₃^--N removal rates of 2.37, 1.28 and 1.7 mg N l^-1 hr^-1, respectively. The ¹⁵N isotope tracer experiment confirmed the aerobic nitrogen removal pathway of strain Z8. Average NO₃^-removal efficiencies were all above 80% in an aerated moving bed bioreactor inoculated with strain Z8 and employed to treat synthetic marine aquaculture wastewater. Metagenomic microbial community analysis revealed that Halomonas sp. Z8 was one of the dominant taxa at genus level, suggesting a vital role in removing nitrate from bioreactor.     

Interpretation: The results of the present study indicate the potential of Halomonas sp. Z8 for treating wastewater in marine re-circulating aquaculture systems.       

Key words: Aerobic denitrification, Aquaculture, Biofiltration, Halomonas sp. Z8, Heterotrophic nitrification

Copyright ? 2020 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).