Chen Can, Wang Jianlong
Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, People's Republic of China.
Appl Microbiol Biotechnol. 2007 Mar;74(3):683-7. doi: 10.1007/s00253-006-0678-x. Epub 2006 Nov 25.
The response of Saccharomyces cerevisiae to different concentrations of Pb(2+) was investigated. The results demonstrated that the growth of S. cerevisiae in the presence of Pb(2+) showed a lag phase much longer than that in the absence of Pb(2+). The inhibition was dependent upon Pb(2+) concentrations. The Pb(2+) at a concentration of 5 microM inhibited the microbial growth by approximately 30% with regard to control, whereas Pb(2+) at concentration of 2 microM did not have a significant effect on the microbial growth. The existence of Pb(2+) did not perturb cell-protein synthesis and there was a good correlation between dry cell weights and total protein content (R (2) = 0.98). The RNA/DNA ratio in the microbial cells varied with Pb(2+) concentration and there was a significant positive correlation between Pb(2+) concentration and the RNA/DNA ratio. The microbial assimilation of ammonium ion was inhibited by the presence of Pb(2+) in the medium; when Pb(2+) concentration was 10 microM, the microbial ammonium assimilation was inhibited about 50%, in comparison with the control experiment.
研究了酿酒酵母对不同浓度Pb(2+)的反应。结果表明，在Pb(2+)存在下酿酒酵母的生长表现出比无Pb(2+)时长得多的延迟期。抑制作用取决于Pb(2+)的浓度。浓度为5 microM的Pb(2+)相对于对照抑制微生物生长约30%，而浓度为2 microM的Pb(2+)对微生物生长没有显著影响。Pb(2+)的存在并未干扰细胞蛋白质合成，并且干细胞重量与总蛋白质含量之间存在良好的相关性（R(2)=0.98）。微生物细胞中的RNA/DNA比率随Pb(2+)浓度而变化，并且Pb(2+)浓度与RNA/DNA比率之间存在显著的正相关。培养基中Pb(2+)的存在抑制了微生物对铵离子的同化作用；与对照实验相比，当Pb(2+)浓度为10 microM时，微生物对铵的同化作用被抑制约50%。
