Effects of electron shuttle (ES) concentration on biofilm formation and redox activity and the molecular mechanism of inducing biofilm formation remain underexplored. Here, we examine the impacts of 2,6-di-tert-butyl-p-benzoquinone (2,6-DTBBQ) on the initial formation and redox activity of biofilms in bioelectrochemical systems (BESs) with Klebsiella quasipneumoniae SP203. The BES with 5-mM 2,6-DTBBQ has higher voltage output (increased approx. 103.53%) than control group, owing to the stimulation of redox reaction and reduction of the internal resistance of BESs. The 10-mM 2,6-DTBBQ enhances biofilm formation but inhibited redox activity of biofilm. Five-millimolar 2,6-DTBBQ promotes the extracellular electron transfer (EET) process with accumulated polysaccharides and high-density protein. CLSM results demonstrates high-density protein catalyze redox activity of biofilm by live/dead cell ratio though no thick biofilm obtained. Moreover, the redox activity and C4-HSL of K. quasipneumoniae SP203 can be stimulated by 2,6-DTBBQ; this strain can respond to 2,6-DTBBQ levels to improve Fe-S clusters/NADH dehydrogenase assembly and the synthesis of NAD and ubiquinone. Based on these results, an EET mechanism of K. quasipneumoniae SP203 is proposed. Collectively, 2,6-DTBBQ can strengthen K. quasipneumoniae SP203 biofilm redox activity and EET, which may contribute to the provision of green energy in the field of low-power supply.

电子穿梭 (ES) 浓度对生物膜形成和氧化还原活性的影响以及诱导生物膜形成的分子机制仍未得到充分探索。在这里，我们研究了 2,6-二叔丁基-对苯醌 (2,6-DTBBQ) 对生物电化学系统 (BES) 中生物膜的初始形成和氧化还原活性的影响，这些生物膜具有准肺炎克雷伯菌SP203。由于氧化还原反应的刺激和 BES 内阻的降低，具有 5-mM 2,6-DTBBQ 的 BES 具有比对照组更高的电压输出（增加约 103.53%）。10-mM 2,6-DTBBQ 增强生物膜形成但抑制生物膜的氧化还原活性。五毫摩尔 2,6-DTBBQ 可促进细胞外电子转移 (EET) 过程，并积累多糖和高密度蛋白质。CLSM 结果表明，虽然没有获得厚生物膜，但高密度蛋白质通过活/死细胞比催化生物膜的氧化还原活性。此外，准肺炎克雷伯菌的氧化还原活性和 C4-HSLSP203可被2,6-DTBBQ刺激；该菌株可以响应 2,6-DTBBQ 水平以改善 Fe-S 簇/NADH 脱氢酶组装以及 NAD 和泛醌的合成。基于这些结果，提出了K. quasipneumoniae SP203 的 EET 机制。总的来说，2,6-DTBBQ 可以增强K. quasipneumoniae SP203 生物膜氧化还原活性和 EET，这可能有助于在低功耗领域提供绿色能源。