Bioalteration of Kraft pine lignin byPhanerochaete chrysosporium

Abstract

Bioalteration of the organic-soluble ether-insoluble fraction of Kraft pine lignin (KL-O) was studied. Various types of inocula ofPhanerochaeta chrysosporium were compared using a standing mode of cultivation under nitrogen limitation. Pellet inoculated and mycelial cultures required a period of about 10 days to become ligninolytically active. When spores were used as inoculum the bioalteration of lignin commenced earlier but the rate was considerably less. The total decrease in absorbance measured amounted to 61% within 20 days after addition of lignin to active mycelial cultures. This corresponded to a reduction of 50% in Klason lignin. Further reduction was possible only when the free lignin was extracted from the culture, purified and mixed with new active cells. Elemental analysis, Klason lignin content, absorptivity coefficient, molecular weight distribution and the presence of saccharides and proteins for free and “cell recovered” lignin were compared with KL-O. Microscopic observation showed the formation of new out-growths in the form of short hyphae appearing concurrently with ligninolytic activity.