United States Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC, 20375, USA.
Defense Threat Reduction Agency, 8725 John J Kingman Rd #6201, Fort Belvoir, VA, 22060, USA.
Microb Biotechnol. 2018 Jan;11(1):98-111. doi: 10.1111/1751-7915.12757. Epub 2017 Jul 11.
Biocathode microbial communities are proposed to catalyse a range of useful reactions. Unlike bioanodes, model biocathode organisms have not yet been successfully cultivated in isolation highlighting the need for culture-independent approaches to characterization. Biocathode MCL (Marinobacter, Chromatiaceae, Labrenzia) is a microbial community proposed to couple CO fixation to extracellular electron transfer and O reduction. Previous metagenomic analysis of a single MCL bioelectrochemical system (BES) resulted in resolution of 16 bin genomes. To further resolve bin genomes and compare community composition across replicate MCL BES, we performed shotgun metagenomic and 16S rRNA gene (16S) sequencing at steady-state current. Clustering pooled reads from replicate BES increased the number of resolved bin genomes to 20, over half of which were > 90% complete. Direct comparison of unassembled metagenomic reads and 16S operational taxonomic units (OTUs) predicted higher community diversity than the assembled/clustered metagenome and the predicted relative abundances did not match. However, when 16S OTUs were mapped to bin genomes and genome abundance was scaled by 16S gene copy number, estimated relative abundance was more similar to metagenomic analysis. The relative abundance of the bin genome representing 'Ca. Tenderia electrophaga' was correlated with increasing current, further supporting the hypothesis that this organism is the electroautotroph.
生物阴极微生物群落被提议催化一系列有用的反应。与生物阳极不同，模型生物阴极生物尚未成功在分离状态下培养，这突出了需要采用非培养方法进行表征。生物阴极 MCL（海洋杆菌属、着色菌科、拉宾西亚菌属）是一种微生物群落，被提议将 CO2 固定与细胞外电子转移和 O2 还原偶联。先前对单个 MCL 生物电化学系统 (BES) 的宏基因组分析导致了 16 个 bin 基因组的解析。为了进一步解析 bin 基因组并比较复制 MCL BES 中的群落组成，我们在稳态电流下进行了鸟枪法宏基因组和 16S rRNA 基因（16S）测序。从复制 BES 中汇集的读取进行聚类，将解析的 bin 基因组数量增加到 20 个，其中超过一半的基因组完整度>90%。未组装的宏基因组读数与 16S 操作分类单元（OTU）的直接比较预测了比组装/聚类宏基因组更高的群落多样性，而且预测的相对丰度不匹配。然而，当将 16S OTU 映射到 bin 基因组上，并根据 16S 基因拷贝数对基因组丰度进行缩放时，估计的相对丰度与宏基因组分析更为相似。代表“Ca. Tenderia electrophaga”的 bin 基因组的相对丰度与电流的增加呈正相关，这进一步支持了该生物是电自养生物的假设。
