Sulfate-reducing microorganisms extensively contribute to the corrosion of ferrous metal infrastructure.There is substantial debate over their corrosion mechanisms.We investigated Fe^(0) corrosion with Desulfovibrio v...Sulfate-reducing microorganisms extensively contribute to the corrosion of ferrous metal infrastructure.There is substantial debate over their corrosion mechanisms.We investigated Fe^(0) corrosion with Desulfovibrio vulgaris,the sulfate reducer most often employed in corrosion studies.Cultures were grown with both lactate and Fe^(0) as potential electron donors to replicate the common environmental condition in which organic substrates help fuel the growth of corrosive microbes.Fe^(0) was corroded in cultures of a D.vulgaris hydrogenase-deficient mutant with the 1:1 correspondence between Fe^(0) loss and H_(2) accumulation expected for Fe^(0) oxidation coupled to H+reduction to H_(2).This result and the extent of sulfate reduction indicated that D.vulgaris was not capable of direct Fe^(0)-to-microbe electron transfer even though it was provided with a supplementary energy source in the presence of abundant ferrous sulfide.Corrosion in the hydrogenase-deficient mutant cultures was greater than in sterile controls,demonstrating that H_(2) removal was not necessary for the enhanced corrosion observed in the presence of microbes.The parental H_(2)-consuming strain corroded more Fe^(0) than the mutant strain,which could be attributed to H_(2) oxidation coupled to sulfate reduction,producing sulfide that further stimulated Fe^(0) oxidation.The results suggest that H_(2) consumption is not necessary for microbially enhanced corrosion,but H_(2) oxidation can indirectly promote corrosion by increasing sulfide generation from sulfate reduction.The finding that D.vulgaris was incapable of direct electron uptake from Fe^(0) reaffirms that direct metal-to-microbe electron transfer has yet to be rigorously described in sulfate-reducing microbes.展开更多
基金supported by the grants from the National Key Research and Development Program of China(No.2020YFA0907300)the National Natural Science Foundation of China(Nos.U2006219 and 52301080).
文摘Sulfate-reducing microorganisms extensively contribute to the corrosion of ferrous metal infrastructure.There is substantial debate over their corrosion mechanisms.We investigated Fe^(0) corrosion with Desulfovibrio vulgaris,the sulfate reducer most often employed in corrosion studies.Cultures were grown with both lactate and Fe^(0) as potential electron donors to replicate the common environmental condition in which organic substrates help fuel the growth of corrosive microbes.Fe^(0) was corroded in cultures of a D.vulgaris hydrogenase-deficient mutant with the 1:1 correspondence between Fe^(0) loss and H_(2) accumulation expected for Fe^(0) oxidation coupled to H+reduction to H_(2).This result and the extent of sulfate reduction indicated that D.vulgaris was not capable of direct Fe^(0)-to-microbe electron transfer even though it was provided with a supplementary energy source in the presence of abundant ferrous sulfide.Corrosion in the hydrogenase-deficient mutant cultures was greater than in sterile controls,demonstrating that H_(2) removal was not necessary for the enhanced corrosion observed in the presence of microbes.The parental H_(2)-consuming strain corroded more Fe^(0) than the mutant strain,which could be attributed to H_(2) oxidation coupled to sulfate reduction,producing sulfide that further stimulated Fe^(0) oxidation.The results suggest that H_(2) consumption is not necessary for microbially enhanced corrosion,but H_(2) oxidation can indirectly promote corrosion by increasing sulfide generation from sulfate reduction.The finding that D.vulgaris was incapable of direct electron uptake from Fe^(0) reaffirms that direct metal-to-microbe electron transfer has yet to be rigorously described in sulfate-reducing microbes.
