title: Sulfate reduction and copper precipitation by a Citrobacter sp. isolated from a mining area.
abstract: A strain of sulfate-reducing bacteria, designated strain 'DBM', was isolated from sediments of a mining area. Phylogenetic analysis of the 16S rRNA gene sequence of the isolate revealed that it was related to members of the genus Citrobacter, with C. AzoR-4, C. freundii, C. braakii and C. werkmanii being the most closely related species (sequence similarity up to 98%). Few studies have been done on sulfate reduction ability in Citrobacter. Electron microscopy studies showed that the morphology of the strain DBM was rod-shaped. Strain DBM reduced 10mM of sulfate completely to sulfide within 7d, and it recovered its sulfate reduction ability after 7d of aerobic growth. Furthermore, strain DBM effectively precipitated 0.40 mM copper during its growth. Elemental composition of the resulting microbial precipitate was studied using electro-dispersive X-ray spectroscopy, and it was found that the ratio of S:Cu was 1.07. The result was consistent with the formation of copper sulfide. Heavy metal precipitation by Citrobacter sp. strain DBM was a phenomenon that may be useful in the bioremediation of acid mine drainage.
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, China. eesqrl@mail.sysu.edu.cn
authors.forename: Rongliang
authors.initials: R
authors.lastname: Qiu
authors.forename: Benliang
authors.initials: B
authors.lastname: Zhao
authors.forename: Jinling
authors.initials: J
authors.lastname: Liu
authors.forename: Xiongfei
authors.initials: X
authors.lastname: Huang
authors.forename: Qingfei
authors.initials: Q
authors.lastname: Li
authors.forename: Eric
authors.initials: E
authors.lastname: Brewer
authors.forename: Shizhong
authors.initials: S
authors.lastname: Wang
authors.forename: Ning
authors.initials: N
authors.lastname: Shi
mesh_terms: D011232:Chemical Precipitation; D002954:Citrobacter / Q000302:isolation & purification*; D003300:Copper / Q000302:isolation & purification*; D019015:Geologic Sediments / Q000382:microbiology; D008906:Mining; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013431:Sulfates / Q000378:metabolism*; D016999:Sulfur-Reducing Bacteria / Q000302:isolation & purification*
chemical_list: D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D003300:Copper