PRODUCTION OF XYLANASES BY ASPERGILLUS-FUMIGATUS AND ASPERGILLUS-ORYZAE ON XYLAN-BASED MEDIA

Aspergillus fumigatus and A. oryzae were cultivated in laboratory fermenters on media containing xylan as the main carbon source. A. fumigatus produced xylanase on unsubstituted, insoluble beech xylan but growth and enzyme production on soluble xylo-oligosaccharides from the steaming of hardwood were poor due to the presence of inhibitors. An essential prerequisite for good xylanase production by A. fumigatus was decrease in the pH of the cultivation below 3.0. At higher pH values, the production of proteolytic enzymes caused degradation of the xylanase activity already produced. A. oryzae produced rather less xylanase activity than A. fumigatus on the beech xylan medium but, after adaptation, was capable of efficient enzyme production on the steamed substrate.