TABLE 1.

Growth of L. lactis MG611-1 (P_I-type proteinase) and L. lactis SH5-1 (P_III-type proteinase) in CDM containing caseins as the sole sources of amino acids

Source of amino acidsa	Growth rate (h−1)b
	L. lactis MG611-1	L. lactis SH5-1
αs1-Casein	NGc	NG
β-Casein	NG	0.09 ± 0.03
κ-Casein	0.77 ± 0.10	0.59 ± 0.08
αs1-Casein + β-casein	0.30 ± 0.09	0.12 ± 0.04
αs1-Casein + κ-casein	0.33 ± 0.03	0.40 ± 0.05
β-Casein + κ-casein	0.91 ± 0.13	0.50 ± 0.10
αs1-Casein + β-casein + κ-casein	0.62 ± 0.04	0.53 ± 0.06
19 free amino acids	1.39 ± 0.06	1.35 ± 0.07

^aCaseins were added to a final concentration of 2.4 g/liter. When a mixture was used, the ratio of α_s1-, β-, and κ-casein was the ratio in milk (i.e., 6:5:2). The amino acid concentration was the amino acid concentration established by Poolman and Konings (29). 

^bMean of three determinations ± confidence limits at P = 0.95. 

^cNG, no growth.