The responses of activities, abundances and community structures of soil denitrifiers to mercury （Hg） stress were investigated through a short-term incubation experiment. Four soil treatments with different concentrations of Hg （CK, Hg25, Hg50, and Hg100, denoted as 0, 25, 50, and 100 mg Hg/kg dry soil, respectively） were incubated for 28 days. Soil denitrification enzyme activity （DEA） was measured at day 3, 7 and 28. The abundances and community structures of two denitrification concerning genes, nirS （cd1-nitrite reductase gene） and nosZ （nitrous oxide reductase gene）, were analyzed using real-time PCR and denaturing gradient gel electrophoresis （DGGE）. Results showed that soil DEA was significantly stimulated in the treatments of Hg25 and Hg50 compared with others at day 7. Meanwhile, no difference in the abundances of soil nirS and nosZ was found between Hg spiked treatments and CK, except the lower abundance of nirS （P 〈 0.05） in the Hg added treatments compared with that in the CK at day 28. The community structures of denitrifiers based on nirS gene presented obvious change at day 7 along with the Hg additions, however, no variation was found in all treatments based on the nosZ gene. The results indicated that Hg （Hg25 and Hg50） had a strongly short-term stimulation on soil DEA, and nirS gene is more sensitive than nosZ gene to Hg stress.
Zhifeng ZhouYuanming ZhengJupei ShenLimei ZhangYurong LiuJizheng He
超高分辨率显微镜成像技术与同位素示踪技术相结合的纳米二次离子质谱技术(NanoSIMS)具有较高的灵敏度和离子传输效率、极高的质量分辨率和空间分辨率(<50 nm),代表着当今离子探针成像技术的最高水平。利用稳定性或者放射性同位素在原位或者微宇宙条件下示踪目标微生物,然后将样品进行固定、脱水、树脂包埋或者导电镀膜处理,制备成可供二次离子质谱分析的薄片,进一步通过NanoSIMS成像分析,不仅能够在单细胞水平上提供微生物的生理生态特征信息,而且能够准确识别复杂环境样品中的代谢活跃的微生物细胞及其系统分类信息,对于认识微生物介导的元素生物地球化学循环机制具有重要意义。介绍了纳米二次离子质谱技术的工作原理和技术路线,及其与同位素示踪技术、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、荧光原位杂交技术(FISH)、催化报告沉积荧光原位杂交技术(CARD-FISH)、卤素原位杂交技术(Halogen In SituHybridization,HISH)等联合使用在微生物生态学研究方面的应用。
