Microbes associated with fuel grade ethanol containment tanks

Microbiologically influenced corrosion (MIC) is known to cause considerable damage to hydrocarbon fuel infrastructure including production, transportation and storage systems. As the production and use of alternative fuels such as fuel grade ethanol (FGE) increase it is important to consider MIC of engineered materials exposed to these ‘newer fuels’ as they enter existing infrastructure. Reports of suspected MIC in systems handling FGE and water prompted an investigation of the microbial diversity associated with these environments. Small subunit ribosomal RNA gene pyrosequencing surveys indicate that acetic-acid-producing bacteria (Acetobacter spp. and Gluconacetobacter spp.) are prevalent in environments exposed to FGE and water. Other microbes previously implicated in corrosion such as sulfate-reducing bacteria and methanogens, were also identified. In addition, acetic-acid-producing microbes and sulfate-reducing microbes were cultivated from sampled environments containing FGE and water. Results indicate that complex microbial communities form in these FGE environments and could cause significant MIC-related damage that may be difficult to control. How to better manage these microbial communities will be a defining aspect of improving mitigation of global infrastructure corrosion.