Biocorrosive Thermophilic Microbial Communities in Alaskan North Slope Oil Facilities

Abstract

Corrosion of metallic oilfield pipelines by microorganisms is a costly but poorly understood phenomenon, with standard treatment methods targeting mesophilic sulfatereducing bacteria. In assessing biocorrosion potential at an Alaskan North Slope oil field, we identified thermophilic hydrogen-using methanogens, syntrophic bacteria, peptideand amino acid-fermenting bacteria, iron reducers, sulfur/thiosulfate-reducing bacteria and sulfate-reducing archaea. These microbes can stimulate metal corrosion through production of organic acids, CO 2 , sulfur species, and via hydrogen oxidation and iron reduction, implicating many more types of organisms than are currently targeted.Micromolar quantities of putative anaerobic metabolites of C 1 -C 4 n-alkanes in pipeline fluids were detected, implying that these low molecular weight hydrocarbons, routinely injected into reservoirs for oil recovery purposes, are biodegraded and provide biocorrosive microbial communities with an important source of nutrients.

Substrate-bound Structures of Benzylsuccinate Synthase Reveal How Toluene Is Activated in Anaerobic Hydrocarbon Degradation

“…In alkyl-SS enzymes, the substitution of alanine for leucine directly adjacent to the presumed binding site of the substrate could make room for the terminal methyl group to shift away from the catalytic cysteine, thus allowing for hydrogen atom abstraction at C2. There have also been proposals of terminal hydrogen atom abstraction in short chain alkanes (40) and even the proposal that methane could be activated by an XSS (41). However, the ability of an alkyl-SS to perform such a dramatically uphill C-H bond cleavage (42) has not been substantiated in vitro to date, and no candidate XSS has been proposed for this reaction.…”

The dual role of microbes in corrosion

“…The use of molecular techniques for community analysis is still rare in corrosion studies. Denaturing gradient gel electrophoresis (DGGE) on corroded iron and oil pipelines (Bermont-Bouis et al, 2007;Duncan et al, 2009;Oliveira et al, 2011;Cote et al, 2014;Marty et al, 2014) showed that the microbial communities involved in corrosion are much more complex than was found so far with culturing methods. Standard metal biocorrosion-monitoring procedures focus mainly on SRB detection, and although SRB are also found in many molecular studies they are not always the most abundant or most relevant microorganisms.…”

Description of Anaerobaculum hydrogeniformans sp. nov., an anaerobe that produces hydrogen from glucose, and emended description of the genus Anaerobaculum

“…Strain OS1 T was the dominant culturable heterotroph, present in the production water at 2.3 cells ml 21 (MPN). The dominant culturable hydrogen oxidizer, Methanothermobacter thermautotrophicus, was present at the same cell density (Duncan et al, 2009). The Hungate agar roll-tube method was used for isolation (Hungate, 1969).…”