Abstract: An exoglucanase (C1), two endoglucanases (Cx) and a β-glucosidase (βG) were isolated from the fermentation broth of two Actinomycete strains in the gut of the termite Odontotermes formosanus. These enzymes were purified sequentially by ammonium sulfate precipitation, and Sephadex G100 and DEAE-Sephadex A50 column chromatographies. Both Actinomycete strains were identified as belonging to Streptomyces spp. based on their morphological, growth, physiological and biochemical characteristics. The molecular masses of C1, two Cx enzymes and βG were determined by SDS-PAGE to be 76.9, 22.3, 66.2 kD and 31.9 kD, respectively. The optimal pH was 5.6 for C1 and 5.0 for Cx and βG, respectively; the optimal reaction temperature was 50 ℃ for Cx and C1, and 40 ℃ for βG, respectively. Moreover, these enzymes retained more than 50% activity even at a temperature as high as 70 ℃. These enzymes could be activated by Fe2+ and Ca2+, but inhibited by Mn2+, Cu2+, Zn2+ and Co2+. These results indicate that these cellulases originated from Streptomyce strains in O. formosanus gut are acidic, heat-tolerant enzymes and that their prosthetic groups may be Fe2+ and Ca2+. Therefore, these enzymes has potential in industrial applications for the decomposition of insoluble cellulose.

Key words: exoglucanase, endoglucanase, β-glucosidase, Streptomyces, Odontotermes formosanus