ИСТИНА

Conversion of protein-containing agricultural waste into vauable substances (food and feed, fertilizers, biomaterials, etc.) is a perspective amd green approach to waste disposal. Еhe most complex, but promising substrates are fibrillar proteins, found in bristles, feathers, ligaments, etc. Bioconversion is a novel green approach consisting in cultivation of bioconverting agents on waste matter, followed by specific and determined decomposition of the substrate for further use.In this work, 17 strains of Aspergillusfungi were assessed as potential bioconverters. First, pre-culture was obtained after 48 hours of cultivation on carbohydrate-rich medium. Then, the biomass was transferred to liquid medium, containing non-specific inductor of proteolysis (fish flour hydrolysate) and cultivated for 96 hours. For culture liquid, elastinolytic, keratinolytic, collagenolytic and general proteolytic activity were measured spectrophotometrically. Later on, the dynamics of proteolytic enzymes’ accumulation was studied for the four most active strains, followed by cultivation of a selected strain with different specific inducers (collagen, elastin, feather meal, keratin hydrolysate, wool), andwithout one. After 48 hours of cultivation, the same activities were measured.The preliminary screening indicated four potential bioconverting strains: A. aureolatus, A. creber, A. jensenii, A. tabacinus. For every strain the peaks of general proteolytic and keratinolytic activities are observed after 96 hours of cultivation (except A. aureolatusand A. jenseniiwith keratinolysis peaks at 72 hours of cultivation). A. aureolatuswas taken for further research and cultivated with specific inducers and without any. When being cultivated without inducer, A. aureolatusexposed high general proteolytic activity (33.15 Uazc), which indicates a presence of constitutive non-specific protease. When growing on keratin-containing media it did not show distinguished keratinolytic activity. However, being cultivated on collagen and elastin, this strain exposed high keratinolytic and collagenolytic activities (27.20 Uker and 26.60 Ucoll, respectively), which demonstratesits potential as a bioconverter of waste fibrillar proteins into valuable biomaterials.