Many factors contribute to the ability of a microbial species to persist when encountering complexly contaminated environments including time of exposure, the nature and concentration of contaminants, availability of nutritional resources, and possession of a combination of appropriate molecular mechanisms needed for survival. Herein we sought to identify genes that are most important for survival of Gram-negative Enterobacteriaceae in contaminated groundwater environments containing high concentrations of nitrate and metals using the metal-tolerant Oak Ridge Reservation (ORR) isolate, Pantoea sp. MT58 (MT58). Survival fitness experiments in which a randomly barcoded transposon insertion (RB-TnSeq) library of MT58 was exposed directly to contaminated ORR groundwater samples from across a nitrate and mixed metal contamination plume were used to identify genes important for survival with increasing exposure times and concentrations of contaminants, and availability of a carbon source. Genes involved in controlling and using carbon, encoding transcriptional regulators, and related to Gram-negative outer membrane processes were among those found to be important for survival in contaminated ORR groundwater. A comparative genomics analysis of 75 Pantoea genus strains allowed us to further separate the survival determinants into core and non-core genes in the Pantoea pangenome, revealing insights into the survival of subsurface microorganisms during contaminant plume intrusion.

中文翻译：

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影响受污染地下水中地下细菌存活的适应度因素


许多因素导致微生物物种在遇到复杂污染环境时能够持续存在，包括暴露时间、污染物的性质和浓度、营养资源的可用性以及拥有生存所需的适当分子机制的组合。在此，我们试图使用耐金属的橡树岭保留地 （ORR） 分离株 Pantoea sp. MT58 （MT58） 来确定对革兰氏阴性肠杆菌科细菌在含有高浓度硝酸盐和金属的受污染地下水环境中存活最重要的基因。生存适应性实验，其中 MT58 的随机条形码转座子插入 （RB-TnSeq） 文库直接暴露于来自硝酸盐和混合金属污染羽流的受污染 ORR 地下水样品中，用于鉴定随着暴露时间和污染物浓度的增加以及碳源的可用性而对生存很重要的基因。参与控制和使用碳、编码转录调节因子以及与革兰氏阴性外膜过程相关的基因被发现对在受污染的 ORR 地下水中生存很重要。对 75 种 Pantoea 属菌株的比较基因组学分析使我们能够进一步将生存决定因素分为 Pantoea 泛基因组中的核心和非核心基因，从而揭示对污染物羽流侵入期间地下微生物生存的见解。