Flavins, including flavin monomucleotide (FMN) and riboflavin, are redox-active compounds found in dissimilatory iron-reducing bacteria growth media, and they are suspected to shuttle electrons between bacteria cells and ferric oxides. AQDS is a commonly used electron shuttle model compound in microbiology. The kinetics of electron transfer between ferrihydrite, lepidocrocite, goethite, or hematite and fully reduced flavins or AH2DS were studied using either stirred batch reactors or a stopped-flow apparatus in the pH range 5-8 in anaerobic chamber. Amorphous ferrihydrite is the most reactive iron oxide with flavins, while goethite is the least reactive. Hematite, which has lower reduction potential than goethite, is an order of magnitude more reactive than goethite. Structure reactivity relationship of initial rates versus reduction potentials of reductants was developed. Effects of pH, raw natural organic matter (NOM), and reduced NOM on reaction rates were studied.

Redox reactions of flavins and AQDS with iron oxides

243rd National Meeting (2012)

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