title: Subcellular distribution and chemical forms of cadmium in a dark septate endophyte (DSE), Exophiala pisciphila.
abstract: Our objective was to understand the cadmium (Cd) tolerance mechanisms by investigating the subcellular distribution, chemical forms of Cd and adsorptive groups in the mycelia of Exophiala pisciphila. We grew E. pisciphila in the liquid media with increasing Cd concentrations (0, 25, 50, 100, 200, and 400 mg L(-1)). Increased Cd in the media caused a proportional increase in the Cd uptake by E. pisciphila. Subcellular distribution indicated that 81 to 97% of Cd was associated with the cell walls. The largest amount and proportion (45-86%) of Cd was extracted with 2% acetic acid, and a concentration-dependent extraction was observed, both of which suggest that Cd-phosphate complexes were the major chemical form in E. pisciphila. A large distribution of phosphate and Cd on the mycelia surface was observed by scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). The precipitates associated with the mycelia were observed to contain Cd by transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX). Fourier transform infrared (FTIR) identified that hydroxyl, amine, carboxyl, and phosphate groups were responsible for binding Cd. We conclude that Cd associated with cell walls and integrated with phosphate might be responsible for the tolerance of E. pisciphila to Cd.
authors.affiliation: College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, People's Republic of China.|Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, 650091, People's Republic of China.
authors.forename: Fangdong
authors.initials: F
authors.lastname: Zhan
authors.affiliation: College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, People's Republic of China.
authors.forename: Yongmei
authors.initials: Y
authors.lastname: He
authors.affiliation: College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, 650091, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.affiliation: Soil and Water Quality Laboratory, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, 33598, USA.
authors.forename: Yun-Ya
authors.initials: YY
authors.lastname: Yang
authors.affiliation: Soil and Water Quality Laboratory, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, 33598, USA.
authors.forename: Gurpal S
authors.initials: GS
authors.lastname: Toor
authors.affiliation: Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, 650091, People's Republic of China. zhaozhw@ynu.edu.cn.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Zhao
mesh_terms: D000220:Adaptation, Biological; D000327:Adsorption; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D060026:Endophytes / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005093:Exophiala / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D025282:Mycelium / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D010710:Phosphates / Q000378:metabolism; D006109:Poaceae / Q000382:microbiology; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D010710:Phosphates; D002104:Cadmium
keywords: Adsorptive groups; Cadmium; Cd-phosphate; Exophiala pisciphila; Subcellular distribution