Thermal stability of xylanases produced by "Aspergillus awamori"

RESUMO

The effect of temperature on the activity and stability of endoxylanase and (beta)-xylosidase from "Aspergillus awamori" was investigated. The growth of "A. awamori" in milled sugar cane bagasse produced predominantly extracellular endoxylanase (30 U/ml) and lower amounts of (beta)-xylosidase (1.3 U/ml). Grown in sugar cane bagasse as the principal carbon source, the microorganism produced a quite stable (beta)-xylosidase in a temperature range of 35-55ºC, but it exhibited a lower thermostable endoxylanase. The thermostability of endoxylanase was enhanced through addition of polyhydric alcohols, mainly 2 M xylitol and sorbitol solutions. Particular stability upon storage (100(per cent)) was found for endoxylanase at -4ºC for 165 days. Yet for (beta)-xylosidase, and activity decrease of approximately 20(per cent) was observed during the first 15 days of storage, maintaining roughly 75(per cent) of initial activity until the end of the experiment.