Bacillus brevis ATCC 9999 sporulated without the production of extracellular protease when grown and allowed to sporulate on nutrient agar plates containing either azo-albumin, casein, or gelatin. Intracellular protease could not be detected in extracts of cells grown in nutrient broth-salts media. However, approximately one-fifth of the level of protease activity in extracts of B. subtilis SB 19 was found in extracts of B. brevis ATCC 9999 grown in minimal media. When protein turnover studies were performed by chasing previously incorporated 14C-l-phenylalanine with a large excess of unlabeled phenylalanine, no protein turnover could be detected if the excess phenylalanine was added at T0 and only a small amount of turnover (1 to 1.6% per hr) was detected if the excess phenylalanine was added at T2.5-2.7. This compares with a measured turnover rate of 8.5% per hr in B. subtilis SB 19 under similar conditions.