Abstract
The suitability of different substrates for Bacillus sp. R2 chitinase activity was tested on various crude and purified chitinous substrates, as well as chitinase storage stability was studied weekly for 2 months at three different temperatures (25, 4 and -20°C). The results revealed that chitinase enzyme of Bacillus sp. R2 catalyzed the hydrolysis of various chitinous substrates, and exhibited greater activity towards the chitins β of Calmar and squid. The temperature -20ºC was the most appropriate temperature for chitinase storage where the enzyme exhibited a relative resistance to freezing and thawing conditions, where its live 4 cycles (4 weeks) with missing 30% from the initial activity. On the other hand, at the temperatures 4 and 25ºC the enzyme retained 43.6% and 44.9% of its initial activity after the first month and 12% and 27.6 after the second month. Concerning the antifungal activity, the chitinase enzyme displayed a mild effect against many saprophytic and plant pathogenic fungi according the descending order: Aspergillus niger > Penicillium degitatum> Aspergillus flavus > Fusarium calmorum > Penicillium sp. >Macrophomira sp. > Rhizoctonia solani. This type of studies characterizes the enzyme for potential pharmaceutically important chitooligosaccharides preparation or promising antifungals production.