Production and characterization of thermostable cellulases from Streptomyces transformant T3-1

A total of 26 thermophilic isolates, selected from a compost of agricultural waste, which was mostly composed of vegetable, corncob and rice straw, were cultivated at 50 degreesC for further studies of thermostable cellulase production. The thermostable cellulase gene from the chromosomal DNA of actinomycetes isolate no. 10 was shotgun-cloned and transformed into Streptomyces sp. IAF 10-164. A transformant, T3-1, was found to be a good strain for the production of thermostable cellulases. Cultivation of T3-1 in modified Mandels-Reese broth containing 1% carboxymethylcellulose (CMC)-sodium salt and the optimal condition for microbial growth were studied. Batch cultivation in a. ask revealed that CMCase and Avicelase production reached the maximum between the third to fifth day, whereas maximum beta-glucosidase production occurred on the ninth day. Microbial biomass increased from the first day to the fifth day and then decreased. The crude enzyme had the highest activity at 50 degreesC and at pH 6.5. The enzyme was shown to be a thermostable cellulase whose activities were stable at 50 degreesC for more than 7 days.