Аннотация:The bioconversion of plant raw materials into highly added value products, as well as the development of new products with advanced characteristics has a high priority for modern biotechnology in the Russian Federation. Deproteinized sunflower meal has been used as a source of carbohydrates and organic nitrogen for the yeast S. cerevisiae fermentation after subsequent acidic and enzymatic treatment. As a result a protein-rich yeast biomass was formed, as well as a liquid fraction, containing non-metabolized pentoses and peptides. These can be used as a medium for further production of probiotics and fodder products. The purpose of this research topic is to study the potential of the filtrate, which is rich with pentoses, for further application as a nutrient medium for microbial fermentation. The efficiency of Bacillus subtilis and Bacillus cereus fermentation was analyzed, according to classical microbiological and biotechnological techniques using both the growth curve and reducing substances accumulation data.