Yu Li Zhi-Han, Luo Xue-Song, Liu Ming, Huang Qiaoyun
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China.
J Basic Microbiol. 2015 Jan;55(1):135-40. doi: 10.1002/jobm.201300390. Epub 2013 Nov 21.
So far, little is known about the diversity of the radiation-resistant microbes of the hyperarid Taklimakan Desert. In this study, ionizing radiation (IR)-resistant bacteria from two sites in Xinjiang were investigated. After exposing the arid (water content of 0.8 ± 0.3%) and non-arid (water content of 21.3 ± 0.9%) sediment samples to IR of 3000 Gy using a (60)Co source, a total of 52 γ-radiation-resistant bacteria were isolated from the desert sample. The 16S rRNA genes of all isolates were sequenced. The phylogenetic tree places these isolates into five groups: Cytophaga-Flavobacterium-Bacteroides, Proteobacteria, Deinococcus-Thermus, Firmicutes, and Actinobacteria. Interestingly, this is the first report of radiation-resistant bacteria belonging to the genera Knoellia, Lysobacter, Nocardioides, Paracoccus, Pontibacter, Rufibacter and Microvirga. The 16s rRNA genes of four isolates showed low sequence similarities to those of the published species. Phenotypic analysis showed that all bacteria in this study are able to produce catalase, suggesting that these bacteria possess reactive oxygen species (ROS)-scavenging enzymes. These radiation-resistant bacteria also displayed diverse metabolic properties. Moreover, their radiation resistances were found to differ. The diversity of the radiation-resistant bacteria in the desert provides further ecological support for the hypothesis that the ionizing-radiation resistance phenotype is a consequence of the evolution of ROS-scavenging systems that protect cells against oxidative damage caused by desiccation.
到目前为止，对于极端干旱的塔克拉玛干沙漠中抗辐射微生物的多样性了解甚少。在本研究中，对来自新疆两个地点的抗电离辐射（IR）细菌进行了调查。使用钴-60源将干旱（含水量为0.8±0.3%）和非干旱（含水量为21.3±0.9%）的沉积物样本暴露于3000 Gy的IR下，从沙漠样本中总共分离出52株抗γ辐射细菌。对所有分离株的16S rRNA基因进行了测序。系统发育树将这些分离株分为五组：噬纤维菌-黄杆菌-拟杆菌、变形菌门、嗜热栖热放线菌、厚壁菌门和放线菌门。有趣的是，这是首次报道属于克诺利亚菌属、溶杆菌属、诺卡氏菌属、副球菌属、Pontibacter、Rufibacter和微枝形杆菌属的抗辐射细菌。四个分离株的16S rRNA基因与已发表物种的基因序列相似性较低。表型分析表明，本研究中的所有细菌都能够产生过氧化氢酶，这表明这些细菌拥有清除活性氧（ROS）的酶。这些抗辐射细菌还表现出多样的代谢特性。此外，发现它们的抗辐射能力有所不同。沙漠中抗辐射细菌的多样性为电离辐射抗性表型是保护细胞免受干燥引起的氧化损伤的ROS清除系统进化结果这一假设提供了进一步的生态学支持。
