TABLE 2.

Growth parameters and proteolytic activity of the wild-type proteolytic strains of S. thermophilus

StrainMean (SD) of growth rate (/h)a during:Duration of the nonexponential phase (min)Proteolytic activityb
1st exponential phase2nd exponential phase
CNRZ 3852.8 (0.18)1.6 (0.03)4027.0
ST13.2 (0.06)1.9 (0.02)604.5
ST22.3 (0.14)1.3 (0.11)10011.2
ST112.8 (0.02)1.6 (0.01)4010.3
ST142.4 (0.01)1.3 (0.01)8018.1
ST162.5 (0.01)1.1 (0.05)8010.0
ST182.9 (0.17)2.2 (0.17)6010.6
  • a From two independent determinations.

  • b Expressed as the percentage of 14C-methylated casein (0.1%, 0.18 μCi/mg) hydrolyzed within 10 min by a cell suspension concentrated to an optical density at 650 nm of 10 (10).