Biosciences Division, Argonne National Laboratory, Argonne, Illinois, USA.
Department of Surgery, The University of Chicago, Chicago, Illinois, USA.
Sci Rep. 2017 Aug 21;7(1):8391. doi: 10.1038/s41598-017-08877-z.
Microbial electrosynthesis is a renewable energy and chemical production platform that relies on microbial cells to capture electrons from a cathode and fix carbon. Yet despite the promise of this technology, the metabolic capacity of the microbes that inhabit the electrode surface and catalyze electron transfer in these systems remains largely unknown. We assembled thirteen draft genomes from a microbial electrosynthesis system producing primarily acetate from carbon dioxide, and their transcriptional activity was mapped to genomes from cells on the electrode surface and in the supernatant. This allowed us to create a metabolic model of the predominant community members belonging to Acetobacterium, Sulfurospirillum, and Desulfovibrio. According to the model, the Acetobacterium was the primary carbon fixer, and a keystone member of the community. Transcripts of soluble hydrogenases and ferredoxins from Acetobacterium and hydrogenases, formate dehydrogenase, and cytochromes of Desulfovibrio were found in high abundance near the electrode surface. Cytochrome c oxidases of facultative members of the community were highly expressed in the supernatant despite completely sealed reactors and constant flushing with anaerobic gases. These molecular discoveries and metabolic modeling now serve as a foundation for future examination and development of electrosynthetic microbial communities.
微生物电化学合成是一种可再生能源和化学生产平台，它依赖于微生物细胞从阴极捕获电子并固定碳。尽管这项技术前景广阔，但栖息在电极表面并在这些系统中催化电子转移的微生物的代谢能力在很大程度上仍然未知。我们从一个主要从二氧化碳生产乙酸盐的微生物电化学合成系统中组装了十三个草图基因组，它们的转录活性被映射到电极表面和上清液中细胞的基因组上。这使我们能够为属于醋杆菌属、硫螺旋菌属和脱硫弧菌属的主要群落成员创建一个代谢模型。根据该模型，醋杆菌属是主要的碳固定者，也是群落的关键成员。在电极表面附近发现了大量来自醋杆菌属的可溶性氢化酶和铁氧还蛋白以及转录物、脱硫弧菌的氢酶、甲酸脱氢酶和细胞色素。尽管反应器完全密封并不断用厌氧气体冲洗，但群落的兼性成员的细胞色素 c 氧化酶在上清液中表达量很高。这些分子发现和代谢建模现在为未来对电合成微生物群落的检查和开发奠定了基础。
