Shewanella oneidensis MR-1 accelerates the corrosion of carbon steel using multiple electron transfer mechanisms

H2is a Major Intermediate inDesulfovibrio vulgarisCorrosion of Iron

“…The inability of the hydrogenase mutant to reduce sulfate with Fe 0 as the electron donor contrasts with electroactive microbes such as Geobacter sulfurreducens (15) or Shewanella oneidensis (18), which continue to utilize Fe 0 as an electron donor even after gene deletions have eliminated the capability for H 2 uptake. Both G. sulfurreducens and S. oneidensis are capable of direct electron uptake as evidenced from an inhibition of Fe 0 -based respiration when genes for key outer-surface c -type cytochromes are deleted (15, 17, 18). Thus, the lack of sulfate reduction by the D. vulgaris hydrogenase mutant suggests that it is unlikely to support sulfate reduction with direct electron uptake from Fe 0 .…”

“…Sulfate was not reduced in the absence of genes required for H2 uptake, even when previously proposed organic electron shuttles were added. All the microbes that have been previously shown to be capable of direct electron uptake from Fe 0 have outersurface c-type cytochromes known to be involved in extracellular electron exchange with other donors/acceptors (15)(16)(17)(18)(19). D. vulgaris lacks outer-surface c-type cytochromes (20).…”

“…Direct Fe 0 -to-microbe electron transfer for D. vulgaris has also been proposed (14). Studies with Geobacter (15, 16), Shewanella (17, 18), and Methanosarcina (19) species have provided evidence for direct electron uptake from Fe 0 by: 1) eliminating the possibility that H 2 was serving as an electron shuttle between Fe 0 and cells; and 2) demonstrating with gene deletions that outer-surface c -type cytochromes were required for electron uptake from Fe 0 . In contrast, no studies have previously reported on D. vulgaris corrosion with strains that were unable to use H 2 (7).…”

“…A rigorous strategy to evaluate the possibility of H 2 serving as an intermediary electron carrier is to determine whether strains unable to use H 2 can respire with Fe 0 as the sole electron donor (15, 16, 18, 19, 27). In instances in which the wild-type strain of interest can consume H 2 , this can be accomplished by deleting genes necessary for H 2 uptake (15, 18, 27).…”

“…A rigorous strategy to evaluate the possibility of H 2 serving as an intermediary electron carrier is to determine whether strains unable to use H 2 can respire with Fe 0 as the sole electron donor (15, 16, 18, 19, 27). In instances in which the wild-type strain of interest can consume H 2 , this can be accomplished by deleting genes necessary for H 2 uptake (15, 18, 27). A strain of D. vulgaris in which genes for all of the annotated hydrogenases on the genome were deleted is available as one of a large collection of mutant strains (28).…”