Program in Social Ecology, University of California, Irvine, California 92717.
Appl Environ Microbiol. 1990 Nov;56(11):3266-72. doi: 10.1128/aem.56.11.3266-3272.1990.
Twenty different bacterial isolates obtained from a mercury-contaminated site in Oak Ridge, Tenn., were grown on plate count agar amended with 25 mug of Hg or 3 mug of CH(3)-Hg (R-Hg) per ml. The total cellular RNA was extracted from each isolate by an acid-guanidine-thiocyanate-phenol-chloroform method. The transcripts of merA and merB were detected and quantitated by Northern (RNA) hybridization. A qualitative assay of mercuric reductase was used to confirm the enzyme activity. Low temperature (4 degrees C) with the presence of Hg (25 mug/ml) significantly increased the net merA transcripts of mid-log-phase cells of six environmental isolates. The net merA transcript production by 18 of the isolates increased when they were grown on 50% plate count broth with 15 mug of Hg per ml, but only 8 isolates showed increased production of merB transcripts. The MICs of Hg and R-Hg for 10 methyl mercury-resistant isolates ranged from 45 to 110 mug of Hg and 0.6 to 4.5 mug of R-Hg per ml. R-Hg was able to induce the expression of merB in 70% of methyl mercury-resistant strains.
从田纳西州橡树岭的汞污染地点获得的 20 个不同的细菌分离株在添加 25 微克汞或 3 微克 CH(3)-Hg（R-Hg）/毫升的平板计数琼脂上生长。从每个分离株中通过酸胍-硫氰酸胍-酚-氯仿法提取总细胞 RNA。通过 Northern（RNA）杂交检测和定量 merA 和 merB 的转录物。使用汞还原酶的定性测定来确认酶活性。低温（4°C）存在 Hg（25 微克/毫升）时，6 个环境分离株的对数中期细胞的净 merA 转录物显著增加。当在含有 15 微克/毫升汞的 50%平板计数肉汤中生长时，18 个分离株中的净 merA 转录物产量增加，但只有 8 个分离株显示 merB 转录物产量增加。10 个甲基汞抗性分离株的 Hg 和 R-Hg 的 MIC 值范围为 45 至 110 微克/毫升和 0.6 至 4.5 微克/毫升 R-Hg。R-Hg 能够诱导 70%的甲基汞抗性菌株表达 merB。
