The component composition of S. avermitilis biomass was studied, including avermectin, lipids, proteins, and a polysaccharide complex (murein). It was established that the composition of lipids of S. avermitilis contains predominantly saturated fatty acids – 86%, the content of monounsaturated (palmitic and vaccine) and polyunsaturated (linoleic and α-linolenic) fatty acids is the same and is about 7%. It should be noted the presence of a significant amount of branched chain fatty acids (isoforms) – more than 70% of the total amount of fatty acids. A technique has been developed for isolating the polysaccharide complex from S. avermitilis biomass. Using IR spectroscopy, it was found that the S. avermitilis polysaccharide complex, as well as the chitin-glucan complex isolated from the thallus of the epigeneic lichen of the species Cladonia rangiferina, is built from chitin units – β-N-acetylglucosamine. It was shown that the polysaccharide complex (murein) has a polyampholytic nature and has high sorption properties with respect to the main (methylene blue) and acid (Congo red) dyes. It was also established that the sorption capacity with respect to the dyes under study for the polysaccharide complex S. avermitilis is 2.8–7.6 times higher than for the chitin – glucan complex Cladonia rangiferina. This indicates a significantly higher content of active functional groups (sorption centers) in the murein structure, which allows us to recommend it for use as an effective sorbent (enterosorbent).