The growth, acid production and changes in viable cell count of 8 strains of Leuconstoc mesenteroides were measured in chemically defined medium (CDM) with different carbon sources or skim milk. The results showed that there were significant differences in the growth of these strains in CDM with lactose or galactose as the single carbon source. Strains LM1, LM2, LM4 and LM8 grew well in CDM with lactose as the single carbon source. Strains LM2, LM3, LM5 and LM8 had stronger vitality in CDM with galactose as the single carbon source, but their growth was weaker than that in the presence of lactose. In skim milk, the viable cell count of all experimental strains increased obviously in the early fermentation stage. After 8 h, their growth entered the stable phase, and the pH value at the end of fermentation was above 6.0. While the differences in genes related to lactose and galactose metabolism were preliminarily compared among the strains in this study, the correlation between genes and phenotypes needs to be further analyzed based on lactose hydrolase activity and lactose and galactose residues.

The purpose of this study was to explore the differences in nutritional components and whey protein components between sheep milk and milk from humans and other animal species used for dairy production. The whey protein components of milk from Hu sheep, East Friensian Milk sheep and their F1 hybrid at different stages of lactation were analyzed and compared with those of goat, cow and human milk. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Native-PAGE were used to identify landmark proteins that differed between milk samples. The contents of milk macronutrients like protein, fat and lactose significantly varied between sheep breeds, between lactation stages, and between sheep and other animal species (P < 0.05) and they showed a certain trend. SDS-PAGE showed that β-lactoglobulin and lactoferrin differed between sheep and human milk, α-lactalbumin differed between sheep and goat milk, and immunoglobulin G (IgG) heavy chain differed between sheep and cow milk. Native-PAGE indicated that there was one protein band that differed between sheep and goat whey as well as three ones that differed between sheep milk and human and cow whey.