Colony morphology of two Streptomyces rimosus strains. (Right) S. rimosus ATCC 10970 (NRRL 2234), abbreviated to strain R7. (Left) S. rimosus strain R6, also known as the Zagreb strain, isolated from soil by the Faculty of Food Science and Biotechnology, University of Zagreb. Note the differences in sporulation, an important determinant in developing fermentation parameters and systems for gene exchange.