Dieser Markus, Smith Heidi J, Ramaraj Thiruvarangan, Foreman Christine M
Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, USA.
Department of Chemical & Biological Engineering, Montana State University, Bozeman, MT 59715, USA.
Microorganisms. 2019 Oct 15;7(10):454. doi: 10.3390/microorganisms7100454.
As many bacteria detected in Antarctic environments are neither true psychrophiles nor endemic species, their proliferation in spite of environmental extremes gives rise to genome adaptations. sp. CG23_2 is a bacterial isolate from the Cotton Glacier stream, Antarctica. To understand how sp. CG23_2 has adapted to its environment, we investigated its genomic traits in comparison to genomes of 35 published species. While we hypothesized that genome shrinkage and specialization to narrow ecological niches would be energetically favorable for dwelling in an ephemeral Antarctic stream, the genome of sp. CG23_2 was on average 1.7 ± 0.6 Mb larger and predicted 1411 ± 499 more coding sequences compared to the other spp. Putatively identified horizontal gene transfer events contributed 0.92 Mb to the genome size expansion of sp. CG23_2. Genes with high copy numbers in the species-specific accessory genome of sp. CG23_2 were associated with environmental sensing, locomotion, response and transcriptional regulation, stress response, and mobile elements-functional categories which also showed molecular adaptation to cold. Our data suggest that genome plasticity and the abundant complementary genes for sensing and responding to the extracellular environment supported the adaptation of sp. CG23_2 to this extreme environment.
由于在南极环境中检测到的许多细菌既不是真正的嗜冷菌，也不是本地物种，尽管环境极端，它们的增殖仍导致了基因组适应。CG23_2菌株是从南极棉花冰川溪流中分离出的一种细菌。为了了解CG23_2菌株如何适应其环境，我们将其基因组特征与35个已发表物种的基因组进行了比较研究。虽然我们假设基因组收缩和专门适应狭窄生态位在能量上有利于在短暂的南极溪流中生存，但与其他物种相比，CG23_2菌株的基因组平均大1.7±0.6 Mb，预测的编码序列多1411±499个。推测的水平基因转移事件对CG23_2菌株的基因组大小扩展贡献了0.92 Mb。CG23_2菌株物种特异性辅助基因组中高拷贝数的基因与环境感知、运动、反应和转录调控、应激反应以及移动元件功能类别相关，这些类别也显示出对寒冷的分子适应。我们的数据表明，基因组可塑性以及用于感知和响应细胞外环境的丰富互补基因支持了CG23_2菌株对这种极端环境的适应。
