School of Environment, State Key Laboratory of Urban Water Resources and Environment, Harbin Institute of Technology, Harbin 150090, China.
HOOKE Instruments Ltd., 130033 Changchun, China.
Sci Total Environ. 2021 Mar 25;762:144328. doi: 10.1016/j.scitotenv.2020.144328. Epub 2020 Dec 17.
Understanding the metabolic function of psychrophilic electroactive bacteria is important for the investigation of extracellular electron transfer (EET) mechanisms under low temperatures (4-15 °C). In this study, Raman activated cell ejection coupled high throughput sequencing was used to accurately generate a mini-metagenome of psychrophilic bacterial community. Hierarchical cluster analysis of the Raman spectrum could accurately select the target Geobacter cluster. The high relative abundance of the membrane transport functional genes ftsEX in the biofilm community indicated an adaptation to reduced temperature, which aided survival of the electroactive bacteria under low temperature. The basal metabolism such as citrate cycle and glycolytic pathway maintained the electron pool for the EET process. The identification of iron (III) transport system genes in high abundance indicated their presence in an active metabolic reaction for potential electron transfer process. It showed the potential involvement c-type cytochromes (coxA and cox1) activity in EET. These results indicated that psychrophilic Geobacter had effective EET mediated by c-type cytochromes at low temperatures.
了解嗜冷电活性细菌的代谢功能对于研究低温（4-15°C）下的细胞外电子转移（EET）机制很重要。在这项研究中，采用拉曼激活细胞弹射高通量测序技术，准确地生成了嗜冷细菌群落的小型宏基因组。拉曼光谱的层次聚类分析可以准确地选择目标 Geobacter 簇。生物膜群落中膜转运功能基因 ftsEX 的相对丰度较高，表明其适应了低温，有助于电活性细菌在低温下的生存。柠檬酸循环和糖酵解途径等基础代谢维持了电子库，用于 EET 过程。大量存在的铁（III）转运系统基因的鉴定表明，它们在潜在的电子转移过程的活跃代谢反应中存在。这表明 c 型细胞色素（coxA 和 cox1）活性可能参与了 EET。这些结果表明，嗜冷 Geobacter 在低温下通过 c 型细胞色素进行有效的 EET。
