Characterization of bacterial growth on solid medium with image analysis

Alkaliphilic bacterial strains producing the enzyme cyclodextrin glucanotransferase were cultivated on solid agar medium containing an indicator system detecting the enzyme. The growth of the colony and the surrounding diffusion zone, due to the enzyme, were measured by the image analysis during the cultivation. It was possible to differentiate between relatively similar clones by observing quantitatively the changes at and around the colony. Optimal experimental conditions for such measurements are discussed. The image analysis technique provides a potential tool for characterizing microbes grown on solid media.