Klebsiella pneumoniae is used widely for the production of value-added chemicals from glycerol, and is known as an exoelectrogen with an externally provided electron shuttle. In this study, the metabolic shift in K. pneumoniae L17 by the activation of electrode-based respiration was examined using microbial fuel cells (MFCs). The mRNA expression levels of the related enzymes for glycerol conversion were compared under electrode-driven anaerobic respirational conditions (i.e., MFC) and fermentative conditions (i.e., non-MFC). mRNA expression clearly responded to the electrode-based electron transfer with simultaneous current generation and changes in metabolite production. The NAD⁺-dependent pathways were activated and more acetate (21.7 vs. 14.6 mM), 3-HP (7.6 vs. 5.3 mM) and 1,3-PDO (45.5 vs. 38.1 mM) and less ethanol production were observed under MFC conditions than under non-MFC (39.6 vs 66.7 mM). Stoichiometric metabolic flux analysis was examined in MFC condition. These results suggest that electron excretion to the carbon electrode drives the metabolic pathway shift of K. pneumoniae L17, and can provide an active control strategy for the fermentative pathway of glycerol.

肺炎克雷伯氏菌广泛用于由甘油生产增值化学品，并且被称为外生电子，具有外部提供的电子穿梭。在这项研究中，使用微生物燃料电池（MFCs）检查了肺炎克雷伯氏菌L17通过激活基于电极的呼吸的代谢变化。在电极驱动的厌氧呼吸条件下（即MFC）和发酵条件下（即非MFC），比较了甘油转化相关酶的mRNA表达水平。mRNA的表达明显响应基于电极的电子转移，同时产生电流和代谢产物的变化。NAD ⁺依赖的途径被激活，在MFC条件下比在MFC下观察到更多的乙酸盐（21.7 vs. 14.6 mM），3-HP（7.6 vs. 5.3 mM）和1,3-PDO（45.5 vs. 38.1 mM）和更少的乙醇产生非MFC（39.6 vs 66.7 mM）。在MFC条件下检查化学计量的代谢通量分析。这些结果表明电子排泄到碳电极驱动肺炎克雷伯氏菌L17的代谢途径转移，并可以为甘油的发酵途径提供积极的控制策略。