Middle East Technical University, Biological Sciences, Microbial Ecology Laboratory and Biophysics Laboratory, Ankara 06800, Turkey.
Middle East Technical University, Biological Sciences, Microbial Ecology Laboratory and Biophysics Laboratory, Ankara 06800, Turkey.
Aquat Toxicol. 2014 Oct;155:15-23. doi: 10.1016/j.aquatox.2014.05.027. Epub 2014 Jun 2.
High concentrations of heavy metals can be toxic for bacteria. However, after prolonged exposure, bacteria can become acclimated and begin to be able to grow in the presence of heavy metals. Acclimation can involve alterations of metabolism and molecular structures. Our aim was to examine these alterations in cobalt-acclimated bacteria via attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy on viable samples. Bacillus sp. and Pseudomonas sp. isolated from a temperate shallow lake and a well-established strain of E. coli were investigated. Our results revealed consistent, wide-spread changes in cell membrane and cell wall dynamics of Bacillus sp. and E. coli, including a decrease in peptidoglycan content of Bacillus sp. and increased lipid ordering of the membrane in both bacteria. Furthermore, a decrease in RNA and protein concentrations of Bacillus sp. was measured. All three bacteria studied showed a decrease in conformational freedom of proteins following cobalt acclimation. Interestingly, both Bacillus sp. and E. coli showed slight but significant alterations in their DNA conformations which might imply a methylation-mediated memory formation leading to epigenetic modulation for cobalt adaptation.
重金属浓度过高可能对细菌有毒。然而，经过长时间的暴露，细菌可以适应并开始能够在重金属存在的情况下生长。适应可能涉及代谢和分子结构的改变。我们的目的是通过衰减全反射傅里叶变换红外（ATR-FTIR）光谱法在活细胞样本上研究钴适应细菌的这些变化。从温带浅湖和成熟的大肠杆菌菌株中分离出的芽孢杆菌和假单胞菌进行了研究。我们的结果表明，芽孢杆菌和大肠杆菌的细胞膜和细胞壁动力学发生了一致的、广泛的变化，包括芽孢杆菌的肽聚糖含量减少，两种细菌的膜脂有序性增加。此外，还测量了芽孢杆菌的 RNA 和蛋白质浓度下降。所研究的三种细菌在钴适应后蛋白质的构象自由度都降低了。有趣的是，芽孢杆菌和大肠杆菌的 DNA 构象都有轻微但显著的变化，这可能意味着甲基化介导的记忆形成导致了钴适应的表观遗传调节。
