Main extracellular electron carrier between Desulfovibrio sp. Huiquan2017 and low alloy steels

Abstract

Desulfovibrio species have been proposed to be able to accept electrons from Fe0 via a mediated electron transfer (MET) process. Electron shuttles that mediate MET were investigated by using dialysis bags to separate the low alloy steel EH40 from the bacterium D. sp. Huiquan2017 in the same liquid system. The weight losses of coupons immersed in the bacteria-free side were found to be significantly higher than those in the abiotic media, whereas they were similar when the molecular weight cutoff of the dialysis bags was between 30,000 D and 100 D. In the bacterial culture high consumption of H2 was found, however, riboflavin and flavin mononucleotides were not detected. Furthermore, expressions of genes encoding periplasmic hydrogenases in the biofilms on the EH40 steel were clearly upregulated. These results suggest that the bacterium D. sp. Huiquan2017 may receive electrons from Fe0 via H2 as the main electron shuttle and the periplasmic hydrogenases may be involved in the oxidation of the extracellular-derived H2.