An efficient cellulolytic and acidothermophilic actinobacterium was isolated from soil, adhered to decomposing tree bark and was identified as Streptomyces DSK59. Screening of synthetic media and the media components identified that, a medium based on starch casein minerals containing carboxy methyl cellulose (CMC) and beef extract (BE) could support enhanced cellulase production by the organism. CMC, BE, NaCl, temperature and pH were accounted as significant for cellulase production and these were optimized using a response surface central composite design (CCD). Optimization of cellulase production resulted in an enhancement of endoglucanase activity to 27 IU ml (1). Acidothermophillic Streptomyces cellulase was found to be efficient for hydrolysis of pretreated sorghum stover and liberated 0.413 gg (1) of total reducing sugars which was higher than previously reported sugar yields obtained using fungal enzymes. (C) 2015 Elsevier Ltd. All rights reserved.