title: Detoxification of hexavalent chromate by growing Paecilomyces lilacinus XLA.
abstract: In the study, the capability of Paecilomyces lilacinus XLA (CCTCC: M2012135) to reduce Cr6+and its main antagonistic mechanisms to Cr6+were experimentally evaluated. Activated growing fungus XLA efficiently reduced over 90% Cr6+in the media with Cr6+concentration below 100 mg L-1at pH 6 after 14 days. After 1-day exposure to 100 mg L-1Cr6+, nearly 50% of Cr6+was reduced. Moreover, SO42-stimulated Cr6+reduction, whereas other interferential ions inhibited Cr6+reduction. The interaction mechanisms between XLA and Cr6+mainly involve biotransformation, biosorption, and bioaccumulation, as detected by electron microscopy and chemical methods. The lower concentrations of Cr6+(5 and 50 mg L-1) stimulated the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) level in XLA, respectively, but the higher concentration of Cr6+(150 mg L-1) decreased the enzymatic activities and GSH concentration. The results implied that SOD, CAT and GSH were defensive guards to the oxidant stress produced by Cr6+. All these extracellular/intracellular defense systems endowed XLA with the ability to resist and detoxify Cr6+by transforming its valent species. The fungus XLA could efficiently reduce Cr6+under different environmental conditions (pH, interferential ions, and concentration). Moreover, XLA could endure the high concentration of Cr6+probably due to its high biotransformation capability of Cr6+and intracellular antioxidant systems for the detoxification of ROS generated by external Cr6+. All these results suggested that the fungus XLA can be applied to remediation of Cr6+-contaminated environments.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
authors.forename: Xingjian
authors.initials: X
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: wlchen@mail.hzau.edu.cn.
authors.forename: Wenli
authors.initials: W
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: qyhuang@mail.hzau.edu.cn.
authors.forename: Qiaoyun
authors.initials: Q
authors.lastname: Huang
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001711:Biotransformation; D002374:Catalase / Q000378:metabolism; D002840:Chromates / Q000378:metabolism* / Q000633:toxicity; D005978:Glutathione / Q000378:metabolism; D015386:Hazardous Substances / Q000378:metabolism* / Q000633:toxicity; D008658:Inactivation, Metabolic; D010143:Paecilomyces / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002840:Chromates; D015386:Hazardous Substances; D002374:Catalase; D013482:Superoxide Dismutase; D005978:Glutathione
keywords: Antioxidant system; Cr(6+); Detoxification; Paecilomyces lilacinus; Tolerant mechanism