Biodegradation of Wheat Straw by Lignolytic Fungi

Nutritional worth of wheat straw inoculated with 4 strains of white rot, lignolytic fungi viz. Phonerochaete chrysosporium (PC), Auricularia polytricha (AP), Cyathus stercoreus (CS) and Sporotrichum pulverulentum (SP) was assessed under controlled laboratory conditions. Spawned straw filled in perforated polyethylene bags (500 g straw on DM basis/bag) was incubated at 25°C till the appearance of fruiting bodies. The fruiting bodies of PC, AP, CS and SP appeared on 17, 25, 15 and 23 days, respectively of inoculation. The release of glucose and pentose irrespective of the incubation period was highest (P<0.01) in PC followed by SP and lowest in AP and CS. The release of these monomers, irrespective of fungal strain, increased (P<0.01) linearly with the advancement of incubation period. The phenolic acids increased (P<0.01) almost linearly with the growth of fungal strains. Amongst the 4 strains, CS was highly (P<0.01) lignolytic followed by SP > AP > PC. The concentration of true protein indicated that the mycelia of SP proliferated most effectively (P<0.01) followed by CS > PC > AP. Irrespective of the strain, the DMD was highest (P<0.01) on 5th day of incubation while NDFD was highest on 3rd day of incubation, there after it declined gradually, indicating the fermentation should be stopped within 3–7 days of incubation. Irrespective of the incubation period, the DM degradability was highest (P<0.01) in PC followed by AP lowest in CS, while the NDF degradability was highest (P<0.01) in CS followed by PC and lowest in SP. The DM loss was higher (P<0.01) in SP and PC strains (49.66 and 41.49%) as compared to that in CS (25.02%). Among the 4 strains tested, Cyathus stercoreus (CS) was rated as the best because of its maximum lignolytic and minimum cellulytic and hemicellulytic activity leading to minimum nutrient losses.