Optimization of culture conditions, partial purification and characterization of a new lectin from Aspergillus nidulans

摘要

The effect of culture conditions on lectin activity of Aspergillus nidulans was determined. Higher lectin activity was observed in liquid medium as compared to mycelia from solidified agar cultures. Agitation mode of cultivation resulted in pellet formation of hyphal mass exhibiting only marginal lectin activity. Maximum lectin activity was detected in cultures growing at neutral pH and 30°C temperature for 7 days under stationary condition. Lectin was partially purified using (NH,)2SO, precipitation followed by dialysis and ultrafiltration. Lectin was precipitated at 50% saturation of (NH4),SO,. Ultrafiltration yielded 48% of the total activity with the specific activity of 46.04 + 1.50 titre mg. Partially purified lectin was characterized for specific agglutination of human type A, B, AB, O erythrocytes as well as rat, mice, sheep, goat and pig erythrocytes, and also lymphocytes, splenocytes and microbial cells. Agglutination was also tested with neuraminidase- and protease-treated erythrocytes. Lectin exhibited strong binding affinity to L-fucose, inulin, thiodigalactoside, mucin and asialofetuin.