Biol. attack may contribute considerably to the deterioration of ceramic materials. Esp. lithotrophic bacteria have been demonstrated to be of importance due to the excretion of H2SO4 or HNO3. Corrosion of concrete by biogenic H2SO4 and HNO3 was modeled in a simulation app. The biotest allowed detection within many different types of materials the appropriate ones. Because the biotest includes the interactions of microorganisms and their environment, a part is the ceramic material as substratum; it cannot be replaced by chem. and/or phys. testing.