THE EFFECTS OF CO-FUNGAL CULTURES AND SUPPLEMENTATION WITH CARBOHYDRATE ADJUNCTS ON LIGNIN BIODEGRADATION AND SUBSTRATE DIGESTIBILITY

The ability of three fungal strains (Pleurotus sajor-caju, Phanerochae te chrysosporium, Trametes versicolor) to decrease the lignin content and to enhance in vitro rumen digestibility of lignified spruce sawdus t was assessed. In monoculture solid substrate fermentation (SSF) stud ies, a considerable length of time (6 weeks) elapsed before 4 to 14% l ignin was degraded. In contrast, paired or multiple cultures of these fungi caused an 8 to 16% loss of native lignin within three weeks of i ncubation. There were also synergistic effects on total polysaccharide /hemicellulose degraded by mixed cultures. A similar observation was m ade for in vitro digestibility of fungal fermented samples: Total solu bles (carbohydrate products) which accumulated in cultures were signif icantly higher in mixed cultures than in respective monocultures. In c ontrast, mixtures of cell free enzyme extracts of these fungi did not cause any marked reduction in lignin or cellulose content. Supplementa tion of wood sawdust with carbohydrate adjuncts prior to fungal treatm ent also led to substantial reduction in lignin content and increased substrate digestibility.