ИСТИНА

At present, one of the important problems is a rational use of natural resources. Among diverse organisms, higher fungi are a major source of biologically active natural products. Fungal polysaccharides attract a lot of attention due to their multiple biological properties. The insoluble part of the cell wall of musrooms is a complex of three biopolymers mainly, chitin, glucans and melanin, each of which itself is of a great practical value. Native higher fungi are of interest from the viewpoint of medicinal chemistry and offer valuable raw materials for the synthesis of biologically active substances. Therefore, the isolation, identification, and study of the physicochemical and sorption properties of these natural biopolymers represent a priory field in the investigation of natural compounds. We report the develop scheme for the isolation chitin-glucan and chitin-glucan-melanin complexes from various kind of native biomass of fungi belonging to classes Basidiomycetes and Ascomycetes, and the study their physicochemical and sorption properties. A four-stage procedure for the isolation chitin-containing complexes included deproteinization (2% NaOH + 0.1% sodium stearate, 83-85oC, 2 h), demineralization (1% HCl, 55-60oC, 2h), depigmentaion (5% H2O2 in ammonia (30-35oC, 4 h)), and deglucanization ( 2% NaOH, 83-85oC, 2 h). Variations occurring in the semiproduct composition (the content of water, mineral and organic substances, total nitrogen, and D-glucosamine) during the processing were monitoring. The original raw material and the chitin-containing materials were characterized on the basis of results of Fourier transform infrared spectroscopy, X-ray analysis, and pyrolytic gas chromatography using crustacean chitin as reference compound. The content of chitin in the final products was 70% for A.mellea and 50% for M.esculenta. The possibility of obtaining chitin-containing materials with the required properties by selecting the fungal species and treatment conditions (the succession and repetition of certain stages) is demonstrated. The result obtained that all investigated samples have the structure of α-chitin. However depending on a kind and, especially from a class of a mushroom biomass, final samples have the different ratios of component chains (chitin-glucan-melanin), and in some cases can contain segmental chitosan units. This defines the structural heterogeneity and a degree of orderliness of a material, and also hydrogen bond behavior and macromolecule packing. We report the sorption characteristics isolated biopolymrs in relation to water and ions of heavy metals (Pb2+, Ni2+ and Cd2+). The maximal adsorption capacity of biopolymers is reached in 40-60 minutes and changes in the following order: Pb2+ (0,8-1,0 г/г) > Cd2+ (0,5-0,87 г/г) > Ni2+ (0,2-0,3 г/г). In case of Pb2+ and Cd2+ the adsorption capacity of polymer depends on the scheme of processing of a fungal biomass and type of a mushroom. It is found that adsorption mechanisms of Pb2+ and Cd2+ and ions Ni2+ are various. We proposed possible mechanisms of the metal adsorption on the investigated biopolymers.