| Summary: | The mechanism behind how flavin mononucleotide (FMN)-producing bacteria attach to a host intestine remains unclear. In order to address this issue, this study isolated the Gram-positive bacteria <i>Lactobacillus plantarum</i> from Mongolian fermented Airag, named <i>L</i>. <i>plantarum</i> MA. These bacteria were further employed as the model microbes, and their electrogenic properties were first identified by their significant expression of type II NADH-quinone oxidoreductase. This study also demonstrated that the electrical activity of <i>L. plantarum</i> MA can be conducted through flavin mononucleotide (FMN)-based extracellular electron transfer, which is highly dependent on the presence of a carbon source in the medium. Our data show that approximately 15 µM of FMN, one of the key electron donors for the generation of electricity, can be produced from <i>L. plantarum</i> MA, as they were cultured in the presence of lactulose for 24 h. We further demonstrated that the electrical activity of <i>L. plantarum</i> MA can promote microbial adhesion and can thus enhance the colonization effectiveness of Caco-2 cells and mouse cecum. Such enhanced adhesiveness was attributed to the increased expression of type I collagens in the intestinal epithelium after treatment with <i>L. plantarum</i> MA. This study reveals the mechanism behind the electrogenic activity of <i>L. plantarum</i> MA and shows how the bacteria utilize electricity to modulate the protein expression of gut tissue for an enhanced adhesion process.
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