A thermophilic nitrate-reducing bacterium isolated from production water of a high temperature oil reservoir and its inhibition on sul- fate-reducing bacteria. © 2016 Jin-Feng Liu, et al. This is an Open Access article distributed under the terms of the Creative Commons Attribu- tion-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by- nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 35 RESEARCH ARTICLE A thermophilic nitrate-reducing bacterium isolated from production water of a high temperature oil reservoir and its inhibition on sulfate-reducing bacteria Jin-Feng Liu 1,4 , Wei-Lin Wu 2 , Feng Yao 2 , Biao Wang 2 , Bing-Liang Zhang 1 , Serge Maurice Mbadinga 1,4 , Ji-Dong Gu 3 and Bo-Zhong Mu 1,4* 1 State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai, People’s Republic of China 2 Institute of Petroleum Engineering and Technology, Jiangsu Oilfield, Yangzhou 225009, Jiangsu Province, People’s Republic of China 3 School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, People’s Republic of China 4 Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai 200237, People’s Republic of China Abstract: A thermophilic spore-forming facultative anaerobic bacterium, designated as Njiang2, was isolated from the production water of a high temperature oil reservoir (87°C). The physiological, biochemical and 16S rRNA gene based phylogenetic analysis indicated that Njiang2 belonged to the genus Anoxybacillus. Njiang2 could significantly inhibit H 2 S production when co-cultured with Desulfotomaculum sp under laboratory conditions, which implied its great potential in mitigation of brine souring in the oil reservoir and in control of biocorrosion caused by sulfate-reducing bacteria. As far as we know, this might be the first report of Anoxybacillus sp. isolated from high temperature oilfield. Keywords: Anoxybacillus, thermophilic, 16S rRNA gene analysis, nitrate-reducing bacterium, souring mitigation, mi- crobial influenced corrosion *Correspondence to: Bo-Zhong Mu, State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China Uni- versity of Science and Technology, Shanghai 200237, People’s Republic of China; E-mail: bzmu@ecust.edu.cn Received: February 19, 2016 ; Accepted: July 7, 2016 ; Published Online: November 17, 2016 Citation: Liu J-F, Wu W-L, Yao F, et al. 2016, A thermophilic nitrate-reducing bacterium isolated from production water of a high temperature oil reservoir and its inhibition on sulfate-reducing bacteria. Applied Environmental Biotechnology, vol.1(2): 35–42. http://dx.doi.org/10.18063/AEB.2016.02.004. 1. Introduction il reservoir souring and microbial induced/ influenced corrosion (MIC), mainly caused by sulfate-reducing bacteria (SRB), are being given more and more attentions by the oil industry, and control on the growth and activity of SRB is of great importance. Studies demonstrate that supp- lement of nitrate to injection water is an effective me- thod to inhibit H 2 S production and control the activ- ities of SRB in the oil production system. Nitrate ad- dition can stimulate the nitrate-reducing bacteria (NRB), a competitive group of anaerobic bacteria, which out- compete SRB and hence suppress the activities of SRB and/or remove sulfide [1–3] . The mechanism on the mitigation of souring by in- jection of nitrate or nitrite has been investigated [4–10] . Obviously, NRB plays an important role in mitigation O