Neutrophilic Iron-Oxidizing "Zetaproteobacteria" and Mild Steel Corrosion in Nearshore Marine Environments
Abstract
Microbiologically influenced corrosion (MIC) of mild steel in seawater is an expensive and enduring problem. Little attention has been paid to the role of neutrophilic, lithotrophic, iron-oxidizing bacteria (FeOB) in MIC. The goal of this study was to determine if marine FeOB related to Monprofundus are involved in this process. To examine this, field incubations and laboratory microcosm experiments were conducted. Mild steel samples incubated in nearshore environments were colonized by marine FeOB, as evidenced by the presence of helical iron-encrusted stalks diagnostic of the FeOB Mariprofundus ferrooxydans, a member of the candidate class "Zetaproteobacteria." Temporal in situ incubation studies showed a qualitative increase in stalk distribution on mild steel, suggesting progressive colonization by stalk-forming FeOB. We also isolated a novel FeOB, designated Mariprofundus sp. strain GSB2, from an iron oxide mat in a salt marsh. Strain GSB2 enhanced uniform corrosion from mild steel in laboratory microcosm experiments conducted over 4 days. Iron concentrations (including precipitates) in the medium were used as a measure of corrosion. The corrosion in biotic samples (7.4 +/- 0.1 mM) was significantly higher than that in abiotic controls (5.0 +/- 0.1 mM). These results have important implications for the role of FeOB in corrosion of steel in nearshore and estuarine environments. In addition, this work shows that the global distribution of Zetaproteobacteria is far greater than previously thought.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 16, 2011
- Accession Number
- ADA537195
Entities
People
- Brenda J. Little
- David Emerson
- Joyce M. Mcbeth
- Katherine M. Farrar
- Richard I. Ray
Organizations
- United States Naval Research Laboratory