Comparative proteomic study of casein micelles in human and animal milks for infant nutrition improvement

Human milk represents the native requirements of infants and serves as a valuable reference for enhancing formula. This investigation focuses on examining the proteome and particle size of milk casein micelles (MCMs) in human and eight animal milks (Holstein cattle, buffalo, yak, goat, sheep, camel, horse, and donkey). In the MCMs studied, a total of 792 proteins derived from the micelles were identified, with 27 proteins being shared across human and eight animal milk samples, including lipoprotein lipase and fatty acid synthase, as determined using Upset diagram software. Notably, human MCMs exhibited significantly higher levels of lipid transporters and carbohydrate metabolism regulator. In contrast, the MCMs in specific animal milks showed a significant increase in the abundance of antimicrobial proteins compared with human milk, such as lactoferrin in camel and donkey, lysozyme in horse and donkey. Additionally, the particle size of human MCMs was significantly smaller than that of studied animals. This investigation comprehensively elucidates the proteome variances and particle size disparities in MCMs between human and eight distinct animal species. Our results provided critical insights pertinent to the optimization of infant formula, aligning it more closely with human milk unique composition. • Milk casein micelles proteome between human and eight animal species were compared. • Some lipase-related proteins in milk casein micelles were conservative. • Apolipoproteins and glucose metabolism regulator were more abundant in human milk. • Specific animal milks had larger particle size and more antimicrobial proteins.