Denitrification potential evaluation of a newly indigenous aerobic denitrifier isolated from largemouth bass Micropterus salmoides culture pond

摘要

This work evaluates the application potential of a new indigenous aerobic denitrifier,strain Pseudomonas CW-2,isolated from a largemouth bass culture pond.The rate of ammonium-N removal by strain CW-2 was approximately 97％ at a DO concentration of 5.2 mg/L.Furthermore,when nitrate and ammonia coexisted,the strain gave profity to assimilating ammonia,and thereafter to denitrification.Under optimal cultivation conditions,citrate and acetate were the carbon resources,C/N was 8,dissolved oxygen was 5.2 mg/L,and pH was 7;the removal rate of ammonium reached nearly 90％.The changing patterns of different bacteria in strain CW-2-treated and the control pond water were also compared.Lower levels of ammonia,nitrite,and phosphates were observed in the treated water as compared with the controls.Meanwhile,phylum-level distributions of the bacterial OTUs revealed that Proteobacteria,Bacteroidetes,Planctomycetes,and Nitrospirae continuously changed their relative abundances in relation to carbon and the addition of strain CW-2;this finding implies that the conventional denitrification process was weakened under the effects of carbon or the presence of strain CW-2.We propose that strain CW-2 is a promising organism for the removal of ammonium in intensive fish culture systems,according to our evaluations of its denitrification performance.