Growth-promoting effects of caseinomacropeptide from cow and goat milk on probiotics.

Caseinomacropeptide (CMP), a 7-kDa phosphoglycopolypeptide fragment released from κ-casein during milk renneting, is heterogeneous with respect to post-translational glycosylation. Several studies have reported that CMP has growth-promoting activity on lactic acid bacteria belonging to the genera Bifidobacterium. The aim of this study was to evaluate the effect of glycosylation and sequence variations between bovine and caprine CMP on the growth of two probiotics: Lactobacillus rhamnosus RW-9595-M and Bifidobacterium thermophilum RBL67. The growth-promoting activities of CMP (mixture of glycosylated (gCMP) and non-glycosylated (aCMP) fractions), aCMP and gCMP were measured in a basal minimal culture medium using turbidimetric microplate assay at 37 °C. Supplementation of the culture media at 2 mg/ml significantly improved maximum growth by 1.5 to 1.8 times depending on the strain, the additive (CMP, aCMP, gCMP), and the bovine or caprine origin (P < 0.05). CMP preparations also decreased the time needed to reach the inflexion point of the growth curve and increase the cell density at that time (P < 0.05). The effects of CMP preparations were dose dependent and significantly superior to the effect of bovine β-lactoglobulin added to the culture media. As gCMP and aCMP were as efficient as bovine and caprine CMP (P > 0.1), it was concluded that the presence of oligosaccharides linked to CMP was not essential for growth-promoting activity of CMP.