The role of acetogens in microbially influenced corrosion of steel

Abstract

Microbially influenced corrosion (MIC) of iron (Fe0) by sulfate-reducing bacteria (SRB) has been studied extensively. Through a mechanism, that is still poorly understood, electrons or hydrogen (H2) molecules are removed from the metal surface and used as electron donor for sulfate reduction. The resulting ferrous ions precipitate in part with the sulfide produced, forming characteristic black iron sulfide. Hydrogenotrophic methanogens can also contribute to MIC. Incubation of pipeline water samples, containing bicarbonate and some sulfate, in serum bottles with steel coupons and a headspace of 10% (vol/vol) CO2 and 90% N2, indicated formation of acetate and methane. Incubation of these samples in serum bottles, containing medium with coupons and bicarbonate but no sulfate, also indicated that formation of acetate preceded the formation of methane. Microbial community analyses of these enrichments indicated the presence of Acetobacterium, as well as of hydrogenotrophic and acetotrophic methanogens. The formation of acetate by homoacetogens, such as Acetobacterium woodii from H2 (or Fe0) and CO2, is potentially important, because acetate is a required carbon source for many SRB growing with H2 and sulfate. A consortium of the SRB Desulfovibrio vulgaris Hildenborough and A. woodii was able to grow in defined medium with H2, CO2, and sulfate, because A. woodii provides the acetate, needed by D. vulgaris under these conditions. Likewise, general corrosion rates of metal coupons incubated with D. vulgaris in the presence of acetate or in the presence of A. woodii were higher than in the absence of acetate or A. woodii, respectively. An extended MIC model capturing these results is presented.

The role of bacterial communities and carbon dioxide on the corrosion of steel

“…They found that corrosion rates were higher when sulphate was used as an electron acceptor, instead of nitrate. Mand et al [61] reported a similar result with D. vulgaris and A. woodii, with the latter supplying fixed organic carbon for the former species and increasing corrosion rates over either species grown alone. Recently, Kato et al [62] reported that an acetogen closely related to Sporomusa sphaeroides was capable of utilising electrons directly derived from the oxidation of Fe, thereby increasing corrosion rates.…”

Dominance of Desulfotignum in sulfate-reducing community in high sulfate production-water of high temperature and corrosive petroleum reservoirs

“…In oil production systems, biofilm formation can cause numerous problems, including plugging of reservoirs, corrosion and biodegradation of materials and petroleum souring (Bass and Lappin-Scott, 1997). Often, SRP and methanogens co-exist in petroleum reservoirs, and several methanogens are known as hydrogen scavengers, which could cause and accelerate metal corrosion by removing electrons from the metal surface (Mand et al, 2013). It has been also reported that products such as propionate and acetate not totally consumed by SRB in the biofilm penetrate into the inner layers, providing substrate for methanogenesis (Sun et al, 2014).…”

A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes

“…The acetate requirement of EMIC-mediating SRB in these chemolithotrophic reactions could be satisfied by EMIC-mediating acetogens, which could grow together with EMIC-mediating SRB as a powerful corrosive consortium (Mand, Park, Jack, & Voordouw, 2014).…”