Tian Tian, Fan Xiaoyang, Feng Man, Su Lin, Zhang Wen, Chi Huimei, Fu Degang
State Key Laboratory of Bioelectronics, School of Biomedical Science and Engineering, Southeast University Sipailou 2 Nanjing 210096 China
State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology & Palaeontology, CAS 210008 China.
RSC Adv. 2019 Dec 11;9(70):40903-40909. doi: 10.1039/c9ra08045g. eCollection 2019 Dec 9.
Flavin-mediated extracellular electron transfer was studied in two Gram-positive bacteria: strain DIF1 and strain DIF2. The electrochemical activities of these strains were confirmed using amperometric - curves and cyclic voltammetry (CV). Spent anodes with biofilms in fresh anolytes showed no redox peaks, while new anodes in the spent broth showed relative redox peaks using CV measurements, indicating the presence of a redox electron mediator secreted by bacteria. Adding riboflavins (RF) and flavin mononucleotide (FMN) improved the electron transfer of the microbial fuel cells inoculated with the two strains. The redox peaks indicated that flavins existed in the anolyte, and HPLC analysis showed that RF and FMN were secreted by the two bacterial strains. The concentration of RF increased until the bacteria grew to the log phase in microbial fuel cells. The concentration of RF decreased and that of FMN increased after the log phase. The two strains secreted FMN only in the microbial fuel cell. These results confirmed that the electrochemical activity mediated by flavins and FMN is essential in the extracellular electron transfer process in the strains DIF1 and DIF2.
菌株DIF1和菌株DIF2中研究了黄素介导的细胞外电子转移。使用安培曲线和循环伏安法（CV）证实了这些菌株的电化学活性。在新鲜阳极电解液中带有生物膜的用过的阳极没有显示出氧化还原峰，而在用过的培养液中的新阳极使用CV测量显示出相对的氧化还原峰，表明存在细菌分泌的氧化还原电子介质。添加核黄素（RF）和黄素单核苷酸（FMN）改善了接种这两种菌株的微生物燃料电池的电子转移。氧化还原峰表明阳极电解液中存在黄素，并且高效液相色谱分析表明RF和FMN是由这两种细菌菌株分泌的。在微生物燃料电池中，RF的浓度一直增加直到细菌生长到对数期。对数期之后，RF的浓度下降而FMN的浓度增加。这两种菌株仅在微生物燃料电池中分泌FMN。这些结果证实了黄素和FMN介导的电化学活性在菌株DIF1和DIF2的细胞外电子转移过程中至关重要。
