title: A P450 gene associated with robust resistance to DDT in ciliated protozoan, Tetrahymena thermophila by efficient degradation.
abstract: Analysis of metabolic mechanisms of dichlorodiphenyltrichloroethane (DDT) accumulation and degradation in microorganisms, which could be used to reduce its hazard to higher organisms at the higher in the food chain, have not been investigated. Robust resistance to DDT (grows well in 256 mg/L DDT) and a surprising ability to degrade DDT (more than 70% DDT within 4h) were found in the ciliated protozoan Tetrahymena thermophila. A P450 gene (CYP5013C2) was found to respond specifically to DDT treatment. In the presence of 256 mg/L DDT, cells with overexpressing CYP5013C2 (p450-OE) grew faster and degraded DDT more efficiently than wild-type (WT) cells, while cells with CYP5013C2 partially knocked down (p450-KD) grew slower and exhibited reduced ability to degrade DDT compared to WT cells. Both dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) were detected in cells after exposure to DDT, and the concentration of DDD in the p450-OE strain gradually decreased from 0.5 to 4h. Thus, we argue that this P450 gene (CYP5013C2), by efficiently degrading DDT to DDD, is associated with robust resistance to DDT in Tetrahymena, and that a strain overexpressing this gene has the potential to serve as bioreactor that degrades environmental DDT.
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310018, China. Electronic address: fenglifang@mail.zjgsu.edu.cn.
authors.forename: Lifang
authors.initials: L
authors.lastname: Feng
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Chengjie
authors.initials: C
authors.lastname: Fu
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Dongxia
authors.initials: D
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China. Electronic address: miaowei@ihb.ac.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Miao
mesh_terms: D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D003634:DDT / Q000378:metabolism* / Q000633:toxicity*; D003633:Dichlorodiphenyl Dichloroethylene / Q000032:analysis; D003632:Dichlorodiphenyldichloroethane / Q000032:analysis; D055785:Gene Knockdown Techniques; D016808:Tetrahymena thermophila / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D003633:Dichlorodiphenyl Dichloroethylene; D003577:Cytochrome P-450 Enzyme System; D003634:DDT; D003632:Dichlorodiphenyldichloroethane
keywords: DDT; Degradation; Tetrahymena thermophila; p450 gene