[S5-3] Corrosion by microorganisms on metal surface
Phenomenon of microorganisms affecting corrosion of metal materials is well known, and refers to microbiologically influenced corrosion (MIC). Although sulfate-reducing bacteria are the most widely known corrosive microorganisms, novel types of iron corrosive microorganisms have been recently reported. Such novel type microorganisms cause corrosion by consuming electrons directly from metal materials, which is a novel corrosion mechanism. Because almost of natural environments are nutrient poor environments, the corrosion by such electron-consuming microorganism may affect to actively the corrosion under nutrient poor environments. Furthermore, corrosion of stainless steel in fresh water environment have been sometime observed. Since stainless steel does not chemically corrode at such low chloride concentration, MIC has been suspected as cause of such corrosion. By microbial community analysis, difference of microbial communities between corrosion of zero-valent iron and stainless steel has been revealed. In this lecture, I will introduce about latest knowledge of MIC and microbial activities on stainless steel.