Untersuchungen zur Bildung extrazellulärer Hemicellulasen durch Pseudocercosporella herpotrichoides in vitro

Investigations on the production of extracellular hemicellulases by Pseudocercosporella herpotrichoides in vitroFor all 15 isolates of Pseudocercosporella herpotrichoides investigated, xylanase as well as arabanase activity could be demonstrated. After cultivation of 3 weeks, the activity of the enzymes reached a peak. The activity of xylanase was considerably increased by addition of xylan in comparison to Maltzin as the sole source of carbohydrate. Also the arabanase activity could be increased significantly by addition of araban or xylan as compared to the Maltzin variant. The optimum temperature with regard to activity and stability of xylanase ranged at 50°C. The pH‐optimum for xylanase activity was found to be at pH 5.0, and the enzyme was stable in ° range between pH4.0 and 8.0 (9.0). In case of arabanase, the temperature optimum varied between 40 and 50°C; up to this temperature, the enzyme was also stable. At pH 5.0, the arabanase activity reached its optimum; stability was observed in ‐ pH range between 4.0 and 9.0. In extracts prepared from autoclaved wheat coleoptiles which were inoculated with Pseudocercosporella herpotrichoides , the presence of the enzymes xylanase, arabanase, cellulase and polymethylgalacturonase could be demonstrated. The enzyme activities of the inoculated samples were considerably higher than those of non‐inoculated controls. The differences, in most cases, were statistically significant. Der Deutschen Forchungsgemeinschaft danken wir für finanzielle Unterstützung.