Microbiologically Influenced Corrosion by Halophilic (Salt-loving) Nitrate and Sulfate-reducing Microorganisms

Abstract Microbiologically influenced corrosion (MIC) potential of halophilic (salt-loving) microorganisms have gained increased interests in recent years due to the expansion of industrial operations in saline environments i.e. shale. Survey of multiple shale reservoirs across the continent revealed a number of recurring taxa shared by many geological formations, including members of the genera Halomonas, Halanaerobium, Methanohalophilus and members of the order Desulfovibrionales. In this paper, MIC potential of pure halophilic strains was evaluated and compared with mixed microbial communities at high salinity. Results showed that the MIC potential of the pure nitrate-utilizing strain Halomonas halodenitrificans was low (max: 0.144 mm/yr), but it formed a biofilm layer close to the steel surface. Whereas the highly corrosive sulfate-reducing bacteria Desulfovibrio ferrophilus formed a thick and compact corrosion layer at the same salinity. Results of the mixed microbial community established using enrichments from a Canadian shale oil site revealed a close association between the activities of bacteria from the genus Halanaerobium and the other members of the halophilic community. The data indicate the interdependence between the halophiles will alter the overall MIC mechanism.