Immunoblot detection of chymosin. A. Samples were taken at 48 h from TAPL-4, T7-36 and TG-87 strains grown in MDFA3 medium without (-) or with either 5 g/L casein or 5 g/L CPPs (CPP+). Antichymosin rabbit antibodies were used. The mature protein was identical to the natural bovine chymosin (35.6 kDa). The band of unprocessed prochymosin (barely visible) is also indicated by a bent arrow. B. MDFA3 culture medium supplemented without (-) or with either 5 g/L casein or 5 g/L CPPs (CPP+).