The physical presence of microbial cells on a metal surface, as well as their metabolic activities, can cause Microbiologically Influenced Corrosion or biocorrosion . Having different oxygen concentrations at two locations on a metal causes a difference in electrical potential and consequently corrosion currents. Nonuniform colonization by bacteria results in differential aeration cells.
Stainless steel relies on a stable oxide film to provide corrosion resistance.
When the oxide film is damaged or oxygen is kept from the metal surface, corrosion can occur. Some biofilm bacteria produce corrosive chemicals like acids and hydrogen gas during their metabolism. This group of bacteria reduce sulfate to hydrogen sulfide which corrodes metals. SRBs can grow in water trapped in stagnant areas, such as dead legs of piping. Inc. 819 Bakke Ave.