Tao Lan-Lan, Xiang Yu-Ping, Wang Ding-Yong, Huang Man-Lin, Shen Hong
College of Resources and Environment, Southwest University, Chongqing 400716, China.
Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Region, Chongqing 400716, China.
Huan Jing Ke Xue. 2016 Nov 8;37(11):4389-4394. doi: 10.13227/j.hjkx.201603198.
A strain with the ability to methylate mercury under both the aerobic and anaerobic conditions was isolated from soil of the water-level-fluctuation-zone in the Three Gorge Reservoir in Shibaozhai Village, Zhongxian Country, Chongqing, China (E108°12'3″ and N30°24'36″). The soil was classified as Purple soil with a pH of 7.97 (0-20 cm depth). The isolation was performed under 1.0 mg·L HgCl conditions. After its morphological and physiological characterization, and its phylogenetic analysis using 16S rDNA gene sequence, the strain was identified as sp., and named as XD-MeHg-B (GenBank accession number: KU954349). On one hand, at 30℃ under aerobic condition, the concentration of methylmercury (MeHg) in the PBS (phosphate buffer saline) solution, which was inoculated with 1×10 cfu·mL suspension of XD-MeHg-B and an initial Hg of 200 ng·L, was exponentially increased to 1.22 ng·L±0.15 ng·L after 60 min incubation and then approached to the maximum of 3.85 ng·L±0.33 ng·L 160 min after incubation. The largest mercury methylation rate was 1.93%. On the other hand, at 30℃ under anaerobic condition, the concentration of MeHg in the PBS solution, which was also inoculated with 1×10 cfu·mL suspension of XD-MeHg-B and an initial Hg of 200 ng·L, was 2.86 ng·L±0.73 ng·L and the largest mercury methylation rate was 1.43% 180 min after incubation. As a result, XD-MeHg-B showed its ability to methylate mercury under both aerobic and anaerobic conditions while with a comparatively hysteretic and lower ability of mercury methylation. These results demonstrated that XD-MeHg-B could be a promising candidate for further studies on mercury biogeochemical cycle, particularly under dry-wet alternative conditions.
从中国重庆忠县石宝寨村三峡水库消落带土壤（东经108°12′3″，北纬30°24′36″）中分离出一株在好氧和厌氧条件下均具有甲基化汞能力的菌株。该土壤被归类为紫色土，pH值为7.97（0 - 20厘米深度）。分离在1.0 mg·L HgCl条件下进行。经过形态学和生理学特征鉴定，以及使用16S rDNA基因序列进行系统发育分析后，该菌株被鉴定为 sp.，并命名为XD-MeHg-B（GenBank登录号：KU954349）。一方面，在好氧条件下30℃时，接种1×10 cfu·mL XD-MeHg-B悬浮液且初始汞含量为200 ng·L的PBS（磷酸盐缓冲盐水）溶液中，甲基汞（MeHg）浓度在孵育60分钟后呈指数增长至1.22 ng·L±0.15 ng·L，然后在孵育160分钟后接近最大值3.85 ng·L±0.33 ng·L。最大汞甲基化率为1.93%。另一方面，在厌氧条件下30℃时，同样接种1×10 cfu·mL XD-MeHg-B悬浮液且初始汞含量为200 ng·L的PBS溶液中，孵育180分钟后MeHg浓度为2.86 ng·L±0.73 ng·L，最大汞甲基化率为1.43%。结果表明，XD-MeHg-B在好氧和厌氧条件下均具有甲基化汞的能力，但汞甲基化能力相对滞后且较低。这些结果表明，XD-MeHg-B可能是进一步研究汞生物地球化学循环，特别是干湿交替条件下汞生物地球化学循环的有前途的候选菌株。
