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Isolation and identification of arsenite oxidizing bacterium DWY-1 and the possible mechanism involved in remediating arsenic-contaminated paddy soil
Received:June 06, 2018  
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KeyWord:arsenic;microorganism;arsenite oxidation;denitrification;arsenic-contaminated paddy soil;remediation
Author NameAffiliationE-mail
ZHOU Wu-xian Institute of Chinese Herbal Medicines, Hubei Academy of Agricultural Sciences, Enshi 445000, China
Chinese Herbal Medicine Subcenter of Hubei Agricultural Science and Technology Innovation Centre, Enshi 445000, China 
 
DUAN Yuan-yuan Institute of Chinese Herbal Medicines, Hubei Academy of Agricultural Sciences, Enshi 445000, China
Chinese Herbal Medicine Subcenter of Hubei Agricultural Science and Technology Innovation Centre, Enshi 445000, China 
 
YOU Jing-mao Institute of Chinese Herbal Medicines, Hubei Academy of Agricultural Sciences, Enshi 445000, China
Chinese Herbal Medicine Subcenter of Hubei Agricultural Science and Technology Innovation Centre, Enshi 445000, China 
 
ZHAO Shi-chen College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing 210095, China 
 
LU Chao Institute of Chinese Herbal Medicines, Hubei Academy of Agricultural Sciences, Enshi 445000, China
Chinese Herbal Medicine Subcenter of Hubei Agricultural Science and Technology Innovation Centre, Enshi 445000, China 
 
LUO Xiao-rong Institute of Chinese Herbal Medicines, Hubei Academy of Agricultural Sciences, Enshi 445000, China
Chinese Herbal Medicine Subcenter of Hubei Agricultural Science and Technology Innovation Centre, Enshi 445000, China 
 
ZHANG Mei-de Institute of Chinese Herbal Medicines, Hubei Academy of Agricultural Sciences, Enshi 445000, China
Chinese Herbal Medicine Subcenter of Hubei Agricultural Science and Technology Innovation Centre, Enshi 445000, China 
emailtoecho@163.com 
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Abstract:
      The aim of this study is to identify a strain for microbial remediation of arsenic (As) -contaminated paddy soil and explore the possible mechanism of arsenite[As (Ⅲ)] oxidizing bacteria in remediating As-contaminated paddy soil under flooded conditions. In this study, some As (Ⅲ) oxidizing bacteria were isolated from the As-contaminated paddy soils collected from different areas in China. We carried out molecular identification, physiological and biochemical analyses on these bacteria, and then used them in remediation experiments on Ascontaminated soil. Six strains capable of oxidizing As (Ⅲ) were isolated. A novel chemoautotrophic As (Ⅲ) -oxidizing bacterium strain, designated as DWY-1, was isolated from an As-contaminated paddy soil in Huangshi City. The physiological and biochemical characteristics showed that the strain DWY-1 was a facultative autotrophic anaerobe, Gram-negative, and belonged to the genus Sinorhizobium. This bacterium could utilize the energy generated from the oxidation of As (Ⅲ) to arsenate[As (Ⅴ)] using O2 or NO3- as the respective electron acceptor for growth under both aerobic and anaerobic conditions. After the addition of cells of strain DWY-1 into the flooded As-contaminated paddy soil for 14 days, the content of As (Ⅲ) in pore water and the phosphoric acid-extractable fraction decreased by 73.0% and 80.0%, respectively. In these samples, the total As content decreased by 32.6% and 32.9%, respectively. In summary, the strain DWY-1 can be a potential resource for the remediation of As-contaminated paddy soil. In the flooded paddy soil, As (Ⅲ) oxidizing bacteria can couple anaerobic As (Ⅲ) oxidation with nitrate reduction and obtain energy from these biological processes for growth. Thus, As (Ⅲ) oxidation mediated by strain DWY-1 is considered as one of the effective ways to remediate As-contaminated soil.