Breastfeeding is essential in the first months of a newborn's life. Breast milk is a source of crucial macronutrients, prebiotic oligosaccharides, and potential probiotic strains of bacteria. Oligosaccharides from breast milk (HMOs) are a significant part of the composition of breast milk and represent a complex of digestible sugars. This study aims to elucidate the enzymatic hydrolysis of these oligosaccharides and other prebiotics by the bacteria present in breast milk. We used modified methods to isolate oligosaccharides (HMOs) from human milk. Using unique techniques, we isolated and identified different bacteria from breast milk, mainly Lactobacillus fermentum. Using enzymatic analyses, we established the participation of α-fucosidase, α-glucosidase, β-galactosidase, and β-glucosidase from breast milk bacteria in the hydrolysis of prebiotic sugars. We also optimized the scheme for isolating oligosaccharides from breast milk by putting the lyophilized product into different food media. We found that the oligosaccharides from breast milk (HMOs) are a potent inducer for the secretion of the studied bacterial enzymes. Also, we found that all the lactobacilli strains we studied in detail could digest mucin-linked glycans. The degradation of these sugars is perhaps a built-in defense mechanism in cases where other sugars are lacking in the environment. We also determined fucosidase activity in some of the isolated strains. We recorded the highest values (2.5 U/mg in L. fermentum ss8) when the medium's oligosaccharides isolated from breast milk were present. Lactobacilli and Bifidobacteria supplied with breast milk are the first colonizers in most cases in the gastrointestinal tract of the newborn. The presence and study of different genes for synthesizing other enzyme systems and transporters of various sugars in this type of bacteria are essential.
Keywords: Lactobacillus; breast milk; enzymes; human milk oligosaccharides; prebiotics.