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Identification of As (Ⅴ)-reducing bacteria from the rhizosphere and tissues of Pteris vittata L.
Received:January 28, 2018  
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KeyWord:arsenic accumulation;arsenic-reducing bacteria;arsC;arsenic bioremediation
Author NameAffiliationE-mail
WANG Jiao College of Resources and Environment, Northwest A & F University, Key Laboratory of Plant Nutrition and Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China  
TIAN Hai-xia College of Resources and Environment, Northwest A & F University, Key Laboratory of Plant Nutrition and Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China  
HE Wen-xiang College of Resources and Environment, Northwest A & F University, Key Laboratory of Plant Nutrition and Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China wenxiang.he@nwafu.edu.cn 
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Abstract:
      Arsenic-reducing bacteria are the main biological factor affecting arsenic transformation in the natural environment. Investigation of the diversity and reduction mechanism of arsenic-reducing bacteria will be an important foundation for arsenic pollution remediation. To obtain aerobic arsenic-reducing bacteria and determine their arsenic-reducing characteristics, four media and two culture methods were employed. The results showed that 23 arsenic-resistant strains from 2 phyla and 10 genera were screened from the rhizosphere and tissues of Pteris vittata L. Most of the isolated bacteria were identified as being from the genus Pseudomonas. The 23 isolated bacterial strains exhibited distinct arsenic resistance and reducing abilities. The As (Ⅴ) -resistance concentration ranged from 80 to 300 mmol·L-1, and the As (Ⅲ) -resistance concentration ranged from 2 to 30 mmol·L-1. In the medium with 1 mmol·L-1 of As (Ⅴ), the 23 isolated bacterial strains reduced 0%~100% of the arsenate to arsenite and removed 3%~79% of the arsenic from the medium. It was found that among these 23 isolated bacterial strains, four of them, i.e., Pseudomonas sp. S2, Pseudomonas sp. P3, Staphylococcus sp. S14, and Agrobacterium sp. P1, were able to remove 75%~79% of the arsenic from the culture medium and reduce more than 81% of the arsenate to arsenite. The arsenicreducing mechanism of all 23 isolated bacterial strains was detected. The arsC gene, which is well known for its involvement in arsenate reduction, was amplified from 21 of the strains, indicating its prevalence in arsenic-reducing bacteria.