Xylanase production by Aspergillus nidulans

When grown on Aspergillus-minimal medium, Aspergillus nidulans secreted a xylanolytic system containing the enzymes necessary for degradation of arabinoxylan. Xylanase (endo-1,4-β-d-xylan-hydrolase; EC 3.2.1.8) production was maximal for cultures at 37°C using oat-spelt xylan and casamino acids as respective carbon and nitrogen sources. SDS-PAGE and overlay techniques revealed the occurrence of two extracellular xylanases (Mr 22 900 and 34 300). Optimum activity was obtained when crude xylanase preparations were incubated for 10 min at pH 5.4 and 55°C. At these conditions the half-life of the xylanase preparation was 3 h.