ACCUMULATION OF EXOPOLYSACCHARIDES BY YEASTS OF RHODOTORULA SP.

Abstract

The work is devoted to the search and assessment of the possibility of using alternative carbon sources for the production of exopolysaccharides by yeasts of the genus Rhodotorula sp. Exopolysaccharides (EPS) are high-molecular polymer metabolites of microorganisms produced on the outside of cells. They have a high ability to gel, emulsify, and suspend. The ability to synthesize EPS has been found in many microorganisms, but their level varies widely both for different EPS producers and for one producer under different cultivation conditions. Therefore, the search for active producer strains, alternative nutrient media, and the development of effective microbial exopolysaccharide technologies is an urgent task of biotechnology. The capabilities of three species of the genus Rhodotorula were evaluated: R.rubra, R.minuta, R.glutinis to secrete and accumulate exopolysaccharides (EPS) on classical Sabouraud's medium with glucose was evaluated. The maximum amount of EPS in the culture fluid of R. minuta was determined. Differential diagnostic Hiss media with maltose, lactose and mannitol were used to determine the use of different carbon-containing substrates by yeast cultures. The ability of all three studied yeast species to use maltose and mannitol as a carbon source was established. Accordingly, these substrates were added to the Sabouraud medium in the amount of 20 g/l, 40 g/l or 60 g/l. It was noted that the maximum amount of EPS in the culture liquid of R. rubra and R. minuta accumulates under the conditions of using 60 g/l of mannitol as a carbon source. For R.glutinis, the highest EPS indicator was established on a medium with 60 g/l of glucose.