A Novel Selective Method for the Production of Bacillus subtilis var. niger Spores

Summary. A method for the recurrent selective production of heat resistant spores of Bacillus subtilis var. niger is described. The method embodies some features of both batch and continuous culture, permitting a daily production of 10 1 volumes of culture containing up to 2·3 × 10 10 spores/ml. These spores are stable in storage at −20° and yet germinate readily, giving rise to easily recognizable, pigmented colonies.