Abstract
One of indispensable conditions for microbiological corrosion to appear is the formation of biofilm on the surface of the metal. That is the biological surficial covering, which contains biologically active microorganisms along with their metabolical compounds. The biofilm is a frequent form of microorganisms existence in water environment. It prevents from diffusion of the metabolic products created by separate cells of microcolonies. It causes that the side products of metabolic changes may gather close to the metal surface. If the metal surface is not resistable to their influence some corrosion processes may occur. The article shows the results of the research of the metallic specimens surface in the environment of three different bacteria types.