| 1株兼具好、厌氧汞甲基化能力细菌的分离鉴定 |
| 摘要点击 1325 全文点击 660 投稿时间：2016-03-26 修订日期：2016-06-07 |
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| 中文关键词 荧光假单胞菌 分离 鉴定 汞甲基化 三峡库区 土壤 消落带 |
| 英文关键词 Pseudomonas fluorescens isolation identification mercury methylation Three Gorge Reservoir soil water-level-fluctuation-zone |
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| 中文摘要 |
| 从三峡水库重庆段忠县石宝寨消落带土壤中，分离纯化后获得1株在好氧和厌氧条件下均能将Hg2+转化成甲基汞的细菌，经过对该菌株的形态特征、理化特征检测及16S rDNA序列分析，初步鉴定其为γ-变形菌纲的荧光假单胞菌，并命名为Pseudomonas fluorescens XD-MeHg-B2（GenBank登录号：KU954349）.通过汞敏感性试验发现该菌对Hg2+极敏感，汞甲基化试验表明，在初始Hg2+浓度为200 ng·L-1的PBS缓冲液中，接种XD-MeHg-B2对数生长期菌悬液，有氧条件下，30℃孵育60 min后，溶液中甲基汞浓度呈指数增高，并在160 min时达到最大，约为3.85 ng·L-1±0.33 ng·L-1，最大汞甲基化率为1.93%；而在厌氧条件下，XD-MeHg-B2同样表现出汞甲基化能力，但其甲基汞的生成较好氧处理显著滞后，且汞甲基化转化率较低，在180min左右甲基汞浓度达到最大，为2.86 ng·L-1±0.73 ng·L-1，最大汞甲基化率为1.43%.综上所述，P.fluorescens XD-MeHg-B2是1株对Hg2+极敏感，兼具好、厌氧汞甲基化能力的细菌，可望为消落带土壤汞生物甲基化的机制研究提供候选菌株，从而为深入研究汞生物地球化学循环、以及正确评价三峡水库蓄水运行后可能带来的汞生态风险评价提供理论依据. |
| 英文摘要 |
| 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-1 HgCl2 conditions. After its morphological and physiological characterization, and its phylogenetic analysis using 16S rDNA gene sequence, the strain was identified as Pseudomonas fluorescens sp., and named as Pseudomonas fluorescens XD-MeHg-B2 (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 1×1011 cfu·mL-1 suspension of P. fluorescens XD-MeHg-B2 and an initial Hg2+ of 200 ng·L-1, was exponentially increased to 1.22 ng·L-1±0.15 ng·L-1 after 60 min incubation and then approached to the maximum of 3.85 ng·L-1±0.33 ng·L-1 160 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 1×1011 cfu·mL-1 suspension of P. fluorescens XD-MeHg-B2 and an initial Hg2+ of 200 ng·L-1, was 2.86 ng·L-1±0.73 ng·L-1 and the largest mercury methylation rate was 1.43% 180 min after incubation. As a result, P. fluorescens XD-MeHg-B2 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 P. fluorescens XD-MeHg-B2 could be a promising candidate for further studies on mercury biogeochemical cycle, particularly under dry-wet alternative conditions. |
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