You Zixuan, Yu Huan, Zhang Baocai, Liu Qijing, Xiong Bo, Li Chao, Qiao Chunxiao, Dai Longhai, Li Jianxun, Li Wenwei, Xin Guosheng, Liu Zhanying, Li Feng, Song Hao
Frontiers Science Center for Synthetic Biology (Ministry of Education), Key Laboratory of Systems Bioengineering, and School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China.
State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, PR China.
ACS Synth Biol. 2025 Feb 21;14(2):373-383. doi: 10.1021/acssynbio.4c00417. Epub 2024 Nov 18.
Microbial electrochemical systems (MESs), as a green and sustainable technology, can decompose organics in wastewater to recover bioelectricity. Electroactive biofilms, a microbial community structure encased in a self-produced matrix, play a decisive role in determining the efficiency of MESs. However, as an essential component of the biofilm matrix, the role of exopolysaccharides in electroactive biofilm formation and their influence on extracellular electron transfer (EET) have been rarely studied. Herein, to explore the effects of exopolysaccharides on biofilm formation and EET rate, we first inhibited the key genes responsible for exopolysaccharide biosynthesis (namely, , , , and ) by using antisense RNA in MR-1. Then, to explore the underlying mechanisms why inhibition of exopolysaccharide synthesis could enhance biofilm formation and promote the EET rate, we characterized cell physiology and electrophysiology. The results showed inhibition of exopolysaccharide biosynthesis not only altered cell surface hydrophobicity and promoted intercellular adhesion and aggregation, but also increased biosynthesis of -type cytochromes and decreased interfacial resistance, thus promoting electroactive biofilm formation and improving the EET rate of . Lastly, to evaluate and intensify the capability of exopolysaccharide-reduced strains in harvesting electrical energy from actual liquor wastewater, engineered strain Δ3171-as3177 was further constructed to treat an actual thin stillage. The results showed that the output power density reached 380.98 mW m, 11.1-fold higher than that of WT strain, which exhibited excellent capability of harvesting electricity from actual liquor wastewater. This study sheds light on the underlying mechanism of how inhibition of exopolysaccharides impacts electroactive biofilm formation and EET rate, which suggested that regulating exopolysaccharide biosynthesis is a promising avenue for increasing the EET rate.
微生物电化学系统（MESs）作为一种绿色可持续技术，能够分解废水中的有机物以回收生物电。电活性生物膜是包裹在自身产生的基质中的微生物群落结构，在决定MESs的效率方面起着决定性作用。然而，作为生物膜基质的重要组成部分，胞外多糖在电活性生物膜形成中的作用及其对细胞外电子转移（EET）的影响鲜有研究。在此，为了探究胞外多糖对生物膜形成和EET速率的影响，我们首先在MR-1中使用反义RNA抑制负责胞外多糖生物合成的关键基因（即 、 、 、 和 ）。然后，为了探究抑制胞外多糖合成可增强生物膜形成并促进EET速率的潜在机制，我们对细胞生理和电生理进行了表征。结果表明，抑制胞外多糖生物合成不仅改变了细胞表面疏水性，促进了细胞间粘附和聚集，还增加了 -型细胞色素的生物合成并降低了界面电阻，从而促进了电活性生物膜的形成并提高了 的EET速率。最后，为了评估和增强胞外多糖减少菌株从实际酒糟废水中获取电能的能力，进一步构建了工程菌株Δ3171-as3177来处理实际稀醪液。结果表明，输出功率密度达到380.98 mW m，比野生型菌株高11.1倍，这表明其具有从实际酒糟废水中获取电能的优异能力。本研究揭示了抑制胞外多糖影响电活性生物膜形成和EET速率的潜在机制，这表明调节胞外多糖生物合成是提高EET速率的一个有前景的途径。
