Investigation of new exopolysaccharides produced by strains of donkey milk

It has been shown that strains of the genus Enterococcus isolated from donkey milk from different regions of the Republic of Armenia have antimicrobial activity, synthesize different polysaccharides and produce disaccharide polymers (glucose and galactose). The quantitative synthesis of polysaccharides (8-15%) depends on the composition of the nutrient medium, temperature and growing time.

Species identification of LAB strains was confirmed by 16S rDNA gene sequencing method using universal primers LAB strains. The methods used for extraction, purification and detection of exopolysaccharides are based on the method of Sørensen et al. (2022). The antibacterial activity of EPS was investigated by agar diffusion assay. Determination of the immunostimulating property was carried out using the ELISA method.

The antimicrobial activity of the polysaccharide and antimicrobial protein-like fractions of the genus Enterococcus strains depends on its concentration, time of interaction with the test culture, and the species of the pathogenic bacteria.

The obtained results were shown that strains isolated from fermented donkey milk that are capable of synthesizing two substances of different nature with high antimicrobial properties during the growth process are promising for further research and application for their use as probiotics and biopreparations in pharmaceuticals.