Sulfate reduction and copper precipitation by a Citrobacter sp. isolated from a mining area

• Published in: Journal of hazardous materials 2009-05, Vol.164 (2), p.1310-1315
• Main Authors: Qiu, Rongliang, Zhao, Benliang, Liu, Jinling, Huang, Xiongfei, Li, Qingfei, Brewer, Eric, Wang, Shizhong, Shi, Ning
• Format: Article
• Language: English
• Subjects: Acid mine drainage; Applied sciences; Chemical Precipitation; Citrobacter; Citrobacter - isolation & purification; Citrobacter sp; Copper - isolation & purification; Copper precipitation; Exact sciences and technology; Geologic Sediments - microbiology; Mining; Phylogeny; Pollution; RNA, Ribosomal, 16S - genetics; Sulfate reduction; Sulfates - metabolism; Sulfur-Reducing Bacteria - isolation & purification
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2008.09.039

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 10 mM of sulfate completely to sulfide within 7 d, and it recovered its sulfate reduction ability after 7 d 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.