Chalmers University of Technology, Department of Architecture and Civil Engineering, Division of Water Environment Technology, SE-412 96, Gothenburg, Sweden.
University of Gothenburg, Chemistry and Molecular Biology, SE-40530, Gothenburg, Sweden.
Sci Rep. 2019 Feb 20;9(1):2356. doi: 10.1038/s41598-018-38006-3.
Biocathodes where living microorganisms catalyse reduction of CO can potentially be used to produce valuable chemicals. Microorganisms harbouring hydrogenases may play a key role for biocathode performance since H generated on the electrode surface can act as an electron donor for CO reduction. In this study, the possibility of catalysing cathodic reactions by hydrogenotrophic methanogens, acetogens, sulfate-reducers, denitrifiers, and acetotrophic methanogens was investigated. The cultures were enriched from an activated sludge inoculum and performed the expected metabolic functions. All enrichments formed distinct microbial communities depending on their electron donor and electron acceptor. When the cultures were added to an electrochemical cell, linear sweep voltammograms showed a shift in current generation close to the hydrogen evolution potential (-1 V versus SHE) with higher cathodic current produced at a more positive potential. All enrichment cultures except the denitrifiers were also used to inoculate biocathodes of microbial electrolysis cells operated with H and bicarbonate as electron acceptors and this resulted in current densities between 0.1-1 A/m. The microbial community composition of biocathodes inoculated with different enrichment cultures were as different from each other as they were different from their suspended culture inoculum. It was noteworthy that Methanobacterium sp. appeared on all the biocathodes suggesting that it is a key microorganism catalysing biocathode reactions.
生物阴极可以利用活微生物来催化 CO 的还原，从而潜在地用于生产有价值的化学物质。含有氢化酶的微生物可能对生物阴极的性能起着关键作用，因为在电极表面产生的 H 可以作为 CO 还原的电子供体。在这项研究中，研究了氢营养型产甲烷菌、乙酸营养型产甲烷菌、硫酸盐还原菌、反硝化菌和乙酸营养型产甲烷菌催化阴极反应的可能性。这些培养物是从活性污泥接种物中富集得到的，并表现出预期的代谢功能。所有的富集物都根据它们的电子供体和电子受体形成了独特的微生物群落。当这些培养物被添加到电化学电池中时，线性扫描伏安曲线显示电流生成在靠近析氢电位（-1 V 相对于 SHE）处发生了偏移，在更正的电位下产生了更高的阴极电流。除了反硝化菌之外的所有富集培养物也被用于接种微生物电解池的生物阴极，这些生物阴极以 H 和碳酸氢盐作为电子受体进行操作，这导致电流密度在 0.1-1 A/m 之间。用不同的富集培养物接种的生物阴极的微生物群落组成彼此之间以及与悬浮培养物接种物之间的差异都很大。值得注意的是，Methanobacterium sp. 出现在所有的生物阴极上，这表明它是一种催化生物阴极反应的关键微生物。
