Laboratory of Molecular Microbiology and Biotechnology, Department of Biology, and Millennium Institute for Cell Dynamics and Biotechnology, Faculty of Sciences, University of Chile, Santiago, Chile.
Appl Microbiol Biotechnol. 2011 Nov;92(4):761-7. doi: 10.1007/s00253-011-3494-x. Epub 2011 Jul 26.
There is great interest in understanding how extremophilic biomining bacteria adapt to exceptionally high copper concentrations in their environment. Acidithiobacillus ferrooxidans ATCC 53993 genome possesses the same copper resistance determinants as strain ATCC 23270. However, the former strain contains in its genome a 160-kb genomic island (GI), which is absent in ATCC 23270. This GI contains, amongst other genes, several genes coding for an additional putative copper ATPase and a Cus system. A. ferrooxidans ATCC 53993 showed a much higher resistance to CuSO(4) (>100 mM) than that of strain ATCC 23270 (<25 mM). When a similar number of bacteria from each strain were mixed and allowed to grow in the absence of copper, their respective final numbers remained approximately equal. However, in the presence of copper, there was a clear overgrowth of strain ATCC 53993 compared to ATCC 23270. This behavior is most likely explained by the presence of the additional copper-resistance genes in the GI of strain ATCC 53993. As determined by qRT-PCR, it was demonstrated that these genes are upregulated when A. ferrooxidans ATCC 53993 is grown in the presence of copper and were shown to be functional when expressed in copper-sensitive Escherichia coli mutants. Thus, the reason for resistance to copper of two strains of the same acidophilic microorganism could be determined by slight differences in their genomes, which may not only lead to changes in their capacities to adapt to their environment, but may also help to select the more fit microorganisms for industrial biomining operations.
人们对于理解嗜极生物在其所处的高铜环境中如何适应具有极大的兴趣。嗜酸氧化亚铁硫杆菌 ATCC 53993 的基因组与菌株 ATCC 23270 具有相同的铜抗性决定因素。然而，前者的基因组中含有一个 160kb 的基因组岛（GI），而后者则没有。该 GI 包含了一些编码额外的铜 ATP 酶和 Cus 系统的基因。与 ATCC 23270 相比（<25mM），A. ferrooxidans ATCC 53993 对 CuSO4（>100mM）的抗性要强得多。当混合两种菌株的相同数量的细菌并在没有铜的情况下让它们生长时，它们各自的最终数量基本保持相等。然而，在有铜的情况下，与 ATCC 23270 相比，ATCC 53993 的生长明显超过了后者。这种行为最有可能是由于 ATCC 53993 基因组中的 GI 中存在额外的铜抗性基因所致。通过 qRT-PCR 测定，当 A. ferrooxidans ATCC 53993 在铜存在的情况下生长时，这些基因被上调，并在铜敏感型大肠杆菌突变体中表达时被证明是功能性的。因此，同一嗜酸微生物的两个菌株对铜的抗性差异可能是由其基因组中的微小差异决定的，这不仅可能导致它们适应环境的能力发生变化，而且还可能有助于选择更适合工业生物浸出操作的微生物。
