Evaluating the importance of flavin-based electron shuttling in corrosion

Faster microbial corrosion of ferrous metals with flavin amendments has led to the common perception that flavins function as an electron shuttle for extracellular metal-to-microbe electron transfer . Direct examination of this possibility revealed that electron transfer from Fe 0 or X80 carbon steel to flavins or the humic acid analogue anthraquinone-2,6-disulfonate (AQDS) was orders of magnitude slower than proton reduction to H 2 . Stainless steel did not reduce shuttles. Electron shuttles could not serve as the electron donor for sulfate reduction. Riboflavin enhanced Desulfovibrio vulgaris growth on H 2 , suggesting that the primary impact of added flavins is acting as a nutrient. • Critical reevaluation of flavin-mediated electron shuttling in microbial corrosion . • Rates of flavin reduction are significantly slower than H 2 production. • Reduced flavins are ineffective electron donors for sulfate reduction. • Riboflavin promotes the growth of Desulfovibrio vulgaris with H 2 as the electron donor. • Flavin-based microbe corrosion acceleration may be attributed to nutritional effects.