Abstract:

In this study, the specific reduction of CO₂ to acetate in presence of methanogenesis inhibitor 2-bromoethanesulfonate (BES) was studied in a bio-electrochemical system (BES) via a two stage experimental design. During first stage using untreated mixed anaerobic consortia, the methanogenesis was dominated and the CO₂ reduction yielded methane at the maximum rate of 0.95 mmol·L^-1·d^-1 at nearly 55.0% coulombic recovery. Sequences belonging to the family Methanobacteriaceae were dominant at the cathodic electrode. During second stage, BES addition selectively suppressed the growth of methanogens, which resulted in a shift of the dominant activity to acetogenesis with the maximum production rate of 2.22 mmol·L^-1·d^-1 with a recovery of 67.3% of electrons in acetate and hydrogen after two duplicates. The main populations were Rhodocyclaceae (15.1%), Clostridiaceae (11.9%), Comamonadaceae (11.1%) and Sphingobacteriales (11.0%). This study highlighted the importance of inhibition of methanogenesis to manoeuvre microbial structures, which decided the final product profiles during a microbial electro synthesis operation.

Key words: microbial electrosynthesis systems (MES), carbon dioxide reduction, acetogenesis, 2-bromoethanesulfonate (BES), methanogenesis inhibition, control, selectivity, boiprocess

摘要：

研究了利用2-溴乙烷磺酸钠(BES)选择性抑制产甲烷菌,从而提高微生物电化学系统合成乙酸产率的可行性,并对比了BES添加前后阴极室微生物菌群结构的变化。结果表明,厌氧混合菌接种物未经BES处理时甲烷是电化学系统CO₂还原的主导产物,最大生成速率达0.95 mmol·L^-1·d^-1,8 d反应时间甲烷中电子回收率达55.0%,16S rRNA测序结果显示固态阴极的主要菌群为Methanobacteriaceae。BES的添加基本抑制了产甲烷菌的活动,使得乙酸成为主导产物,其合成速率最高达2.22 mmol·L^-1·d^-1,系统总电子回收率达67.3%。Rhodocyclaceae (15.1%),Clostridiaceae(11.9%)、Comamonadaceae(11.1%)和Sphingobacteriales(11.0%)为主要菌群。研究结果表明了微生物电化学合成系统中抑制甲烷生成对调控微生态结构,从而调控电化学终产物的重要性。

关键词: 微生物电化学合成系统, 二氧化碳还原, 乙酸合成, 2-溴乙烷磺酸钠(BES), 甲烷化抑制剂, 控制, 选择性, 生物过程