The present study examines the effects of microorganisms, which are isolated from the clay used in roof tile making by storage, on the plasticity and strength of tile clay, kaolinitic clay and montmorillonitic clay. Following trials done by using live cells and their metabolites, it was observed that bacterial activity had an effect on the plasticity and strength values of clay in both cases. It was also determined that ripening could be accelerated by choosing appropriate bacterial isolates and it was possible to use bacteria in industrial aspects.

Keywords: Bacteria, Clay, Plasticity, Bentonite, Kaolinite.