Ding Qinran, Liu Qijing, Zhang Yan, Li Feng, Song Hao
Frontiers Science Center for Synthetic Biology (Ministry of Education), and Key Laboratory of Systems Bioengineering, Tianjin University, Tianjin300072, China.
Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin300072, China.
ACS Synth Biol. 2023 Feb 17;12(2):471-481. doi: 10.1021/acssynbio.2c00408. Epub 2022 Dec 1.
Efficient extracellular electron transfer (EET) of exoelectrogens is critical for practical applications of various bioelectrochemical systems. However, the low efficiency of electron transfer remains a major bottleneck. In this study, a modular engineering strategy, including broadening the sources of the intracellular electron pool, enhancing intracellular nicotinamide adenine dinucleotide (NADH) regeneration, and promoting electron release from electron pools, was developed to redirect electron flux into the electron transfer chain in MR-1. Among them, four genes include gene encoding a lactate transporter for broadening the sources of the intracellular electron pool, gene encoding a glyceraldehyde-3-phosphate dehydrogenase and gene encoding a malate dehydrogenase in the central carbon metabolism for enhancing intracellular NADH regeneration, and gene encoding NADH dehydrogenase on the inner membrane for releasing electrons from intracellular electron pools into the electron-transport chain. Upon assembly of the four genes, electron flux was directly redirected from the electron donor to the electron-transfer chain, achieving 62% increase in intracellular NADH levels, which resulted in a 3.5-fold enhancement in the power density from 59.5 ± 3.2 mW/m (wild type) to 270.0 ± 12.7 mW/m (recombinant strain). This study confirmed that redirecting electron flux from the electron donor to the electron-transfer chain is a viable approach to enhance the EET rate of .
外排电子菌高效的细胞外电子转移（EET）对于各种生物电化学系统的实际应用至关重要。然而，电子转移效率低下仍然是一个主要瓶颈。在本研究中，开发了一种模块化工程策略，包括拓宽细胞内电子池的来源、增强细胞内烟酰胺腺嘌呤二核苷酸（NADH）的再生以及促进电子从电子池释放，以将电子通量重新导向MR-1中的电子传递链。其中，四个基因包括：一个编码乳酸转运蛋白的基因，用于拓宽细胞内电子池的来源；一个编码甘油醛-3-磷酸脱氢酶的基因和一个编码中心碳代谢中苹果酸脱氢酶的基因，用于增强细胞内NADH的再生；以及一个编码内膜上NADH脱氢酶的基因，用于将细胞内电子池中的电子释放到电子传递链中。在组装这四个基因后，电子通量直接从电子供体重新导向电子传递链，细胞内NADH水平提高了62%，这导致功率密度从59.5±3.2 mW/m（野生型）提高到270.0±12.7 mW/m（重组菌株），提高了3.5倍。本研究证实，将电子通量从电子供体重新导向电子传递链是提高[具体菌名未给出]的EET速率的一种可行方法。
