title: [Research on mercury methylation by Geobacter sulfurreducens and its influencing factors].
abstract: Mercury methylation by Geobacter sulfurreducens and the effects of environmental factors were studied under laboratory conditions. The results showed that G. sulfurreducens could grow well in the presence of low concentrations of mercuric chloride, but its growth was inhibited to a certain extent, mainly expressed in the prolonged lag phase. G. sulfurreducens could transform inorganic mercury into methylmercury, and this process was affected by many environmental factors. The efficiency of mercury methylation reached 38% under anaerobic conditions with 1 mg x L(-1) HgCl2 and 0.9% salinity at 35 degrees C, pH 6.0. Increasing the initial HgCl2 concentration or salinity in an appropriate manner improved mercury methylation, but the concentration of methylmercury reduced when the concentrations of HgCl2 and salinity were too high. The efficiency of mercury methylation increased with the increasing temperature in range of 4-35 degrees C. Weakly acidic environment was more beneficial to mercury methylation than acidic, neutral or alkaline conditions. In addition, the efficiency of mercury methylation was also affected by humic acid and cysteine. Humic acid inhibited mercury methyaltion, whereas cysteine could improve the efficiency of mercury methylation. This study provided a direct evidence for mercury methylation mediated by iron-reducing bacteria in the natural aquatic ecosystem.
authors.affiliation: School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China. zouyanlucy@163.com
authors.forename: Yan
authors.initials: Y
authors.lastname: Zou
authors.forename: You-Bin
authors.initials: YB
authors.lastname: Si
authors.forename: Xue
authors.initials: X
authors.lastname: Yan
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
mesh_terms: D001673:Biodegradation, Environmental; D004785:Environmental Pollutants / Q000737:chemistry / Q000302:isolation & purification; D045302:Geobacter / Q000145:classification / Q000378:metabolism*; D008627:Mercuric Chloride / Q000737:chemistry / Q000302:isolation & purification; D008628:Mercury / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D008767:Methylmercury Compounds / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004785:Environmental Pollutants; D008767:Methylmercury Compounds; D008627:Mercuric Chloride; D008628:Mercury