Thermal stability of xylanases produced by "Aspergillus awamori"

Lemos, Judith Liliana SolórzanoBon, Elba P. SSantana, Maria de Fátima EbolePereira Junior, Nei

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.