Effect of Storage at 3 C on the Proteinase Enzyme Systems of Slow and Fast Strains of Lactic Streptococci

The ability of stored cells to grow in casein medium or to produce acid in milk at 22 C was retarded following storage at 3 C. Although the number of viable cells remained constant, their proteinase activity also decreased with storage. The proteinase activity of the particulate and soluble fractions from disrupted cells of two slow acid-producing cultures (Streptococcus lactis HI and Streptococcus cremoris KH) decreased with storage at 3 C. The proteinase activity of the particulate fractions of two fast acid-producing cultures (S. lactis AC'-I and S. cremoris US-3) was also labile to storage at 3 C, but the activity of their soluble fractions was unaffected by storage. 1023