The extracellular electron transfer (EET) mechanism of an isolated Gram-positive Bacillus megaterium strain (LLD-1), identified by 16S rRNA gene sequencing and physiological analysis, was investigated in the present study. The electrochemical activity of strain LLD-1 was confirmed by electrochemical E-t and amperometric I-t tests. Flavins in culture suspension from strain LLD-1 were further proved to be able to act as electron shuttles, strengthening the electron transfer from LLD-1 to the electrode. The output voltage and current output were increased 2.8 times and 3.7 times, respectively, by adding 100 nM exogenetic flavins into microbial fuel cells inoculated with LLD-1. Electricity generation by LLD-1 from different carbon sources can be enhanced by adding 100 nM exogenetic flavins. This study indicated that flavins were essential to the EET process of the Gram-positive strain LLD-1. Furthermore, a putative EET model for B. megaterium strain LLD-1 and even for Gram-positive bacteria was proposed.

本研究研究了分离的革兰氏阳性巨大芽孢杆菌菌株（LLD-1）的细胞外电子转移（EET）机制，该菌株通过16S rRNA基因测序和生理分析鉴定。通过电化学E - t和安培I - t证实了LLD-1菌株的电化学活性。测试。进一步证明，菌株LLD-1的培养悬浮液中的黄素能够充当电子穿梭，增强从LLD-1到电极的电子转移。通过向接种LLD-1的微生物燃料电池中添加100 nM外源黄素，输出电压和电流输出分别提高了2.8倍和3.7倍。通过添加100 nM外源黄素可以增强LLD-1从不同碳源产生的电能。这项研究表明，黄素对于革兰氏阳性菌株LLD-1的EET过程至关重要。此外，提出了针对巨大芽孢杆菌LLD-1甚至革兰氏阳性细菌的推定EET模型。