Conversion of agro-industrial wastes into non-toxic protein-rich food additives by basidial fungi strains isolated from diverse ecosystems of Georgia

Great interest to basidial fungi is determined by their potential to convert number of lignocellulosic wastes into nontoxic compounds, cheap food, pharmaceuticals, etc. The majority of basidial fungi strains are characterized by high activity of enzymes degrading plant biopolymers, including lignin, which attracts special attention because of their use in different industries and medicine. Among 53 tested basidial fungi strains best results were obtained by Pleurotus drynus IN11 and Ganoderma sp. GV02 strains while growing on orange wastes, where 20% and 27% of protein, respectively, and up to 50% of carbohydrates were accumulated. After 10 - 20 days of solid state fermentation (SSF) in the same biomass the content of lignin was detected only in trace amounts. The content of microelements was (mg/kg): calcium 1200 - 6200, potassium 2100 - 2800, and sodium 90 - 708. Further investigation of strains allowed selection of active producers of soluble polysaccharides among which Pleurotus ostreotus and the representatives of genus Ganoderma sp. (10 - 14 g/L) were the most active. During the submerged fermentation (SF) the highest potential to produce extracellular antioxidants were detected in several strains of Ganoderma sp. (up to 6 g/L). Some selected Ganoderma strains expressed very high laccase extracellular activity (about 125000 U/L).