Isolation of Acetogenic Bacteria That Induce Biocorrosion by Utilizing Metallic Iron as the Sole Electron Donor

Abstract

cCorrosion of iron occurring under anoxic conditions, which is termed microbiologically influenced corrosion (MIC) or biocorrosion, is mostly caused by microbial activities. Microbial activity that enhances corrosion via uptake of electrons from metallic iron [Fe(0)] has been regarded as one of the major causative factors. In addition to sulfate-reducing bacteria and methanogenic archaea in marine environments, acetogenic bacteria in freshwater environments have recently been suggested to cause MIC under anoxic conditions. However, no microorganisms that perform acetogenesis-dependent MIC have been isolated or had their MIC-inducing mechanisms characterized. Here, we enriched and isolated acetogenic bacteria that induce iron corrosion by utilizing Fe(0) as the sole electron donor under freshwater, sulfate-free, and anoxic conditions. The enriched communities produced significantly larger amounts of Fe(II) than the abiotic controls and produced acetate coupled with Fe(0) oxidation prior to CH 4 production. Microbial community analysis revealed that Sporomusa sp. and Desulfovibrio sp. dominated in the enrichments. Strain GT1, which is closely related to the acetogen Sporomusa sphaeroides, was eventually isolated from the enrichment. Strain GT1 grew acetogenetically with Fe(0) as the sole electron donor and enhanced iron corrosion, which is the first demonstration of MIC mediated by a pure culture of an acetogen. Other well-known acetogenic bacteria, including Sporomusa ovata and Acetobacterium spp., did not grow well on Fe(0). These results indicate that very few species of acetogens have specific mechanisms to efficiently utilize cathodic electrons derived from Fe(0) oxidation and induce iron corrosion. where ϩ0.82 V and Ϫ0.41 V reference the SHE.The cathodic hydrogen evolution on iron surfaces is usually a particularly slow reaction under neutral pH conditions, because proton availability is limited and the reaction has low electrode potential and high overpotential. Hence, theoretically, iron corrosion in anoxic environments should not be a serious problem. However, iron corrosion in anoxic environments has been reported often and, in most cases, it is thought to be mediated by metabolic activities of microorganisms therein (1-3). Iron corrosion that occurs in this manner is termed microbiologically influenced corrosion (MIC) or biocorrosion. Diverse kinds of microorganisms, including sulfate-reducing bacteria (SRB), Fe(II) oxidizers, Fe(III) reducers, fermenting bacteria, and methanogens, have been reported as contributing to MIC (4-9). These microorganisms induce MIC in a number of ways, including formation of redox/chemical gradient on the iron surfaces, production of corrosive chemicals (e.g., H 2 S and organic acids), degradation of protective coatings on iron surfaces, and acceleration of cathodic reactions (10).Among such diverse MIC mechanisms, acceleration of cathodic reactions, often referred to as cathodic depolarization, was first proposed in the 1930s and has been considered one of the most promine...

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

“…EMIC is not limited to SRB, but may also involve corrosive strains of genera of hydrogenotrophic methanogens (Daniels, Belay, Rajagopal, & Weimer, 1987;Uchiyama, Ito, Mori, Tsurumaru, & Harayama, 2010) or of acetogens (Kato, Yumoto, & Kamagata, 2015). 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).…”

Enhanced microbial electrosynthesis by using defined co-cultures

“…In addition, mixed communities are often reported to show higher electron transfer rates or higher current efficiencies than pure cultures (Dinh et al, 2004;Nevin et al, 2008;Call et al, 2009;Fast and Papoutsakis, 2012;Ganigue et al, 2015). Thus, especially with the possibility to engineer and improve each specialist in the co-culture, a stable and probably faster electrosynthesis system can be achieved compared with engineering existing iron corroding methanogens or homoacetogens (Uchiyama et al, 2010;Kato et al, 2015).…”

“…Besides methanogenic archaea and homoacetogenic bacteria, Fe(0)-corroding microorganisms have been intensively investigated for their outstanding electron transfer capabilities (Dinh et al, 2004;Uchiyama et al, 2010;Enning et al, 2012;Venzlaff et al, 2013;Enning and Garrelfs, 2014;Kato et al, 2015;Beese-Vasbender et al, 2015b). Although direct electron uptake has been proposed in these microorganisms, no mechanism has been identified to date Venzlaff et al, 2013;Enning and Garrelfs, 2014;BeeseVasbender et al, 2015b).…”

Complementary Microorganisms in Highly Corrosive Biofilms from an Offshore Oil Production Facility

“…However, opportunities to study biofilms covering the inner walls of pipe networks of operational oil facilities are scarce; therefore, MIC has been extensively studied in laboratory experiments with metallic coupons or cultures of specific organisms that are potentially involved in MIC (5)(6)(7)(8). Sulfidogenic bacteria (reducing sulfate, thiosulfate, and/or sulfur to sulfide) such as some members of the phylum Deltaproteobacteria (5, 6, 9-11), Firmicutes, or Archaeoglobales (12); specific iron-oxidizing microorganisms (5,6,(13)(14)(15); metalreducing bacteria such as members of the genera Shewanella (16) and Geobacter (17,18); and acid-producing fermentative organisms have been incriminated as major actors in MIC, and different processes have been described (18,19). The main mechanisms of MIC are (i) the reduction of iron to iron sulfide through hydrogen sulfide produced by sulfate-reducing bacteria or archaea in a process referred to as chemical MIC (CMIC) (5,6) and (ii) direct oxidation of iron (Fe 0 ) by specifically adapted lithotrophic microorganisms that withdraw electrons from iron via electroconductive iron sulfide in a process referred to as electrical MIC (EMIC) (6,20).…”