Abstract : As part of the research and production of cellulases and endoglucanases enzymes in microorganisms, ten mesophilic actinomycetes strains were isolated from the Souk Ahras region. After the screening method, the most active strain (S331) was selected for optimization of production conditions. S331 strain grows well on ISP2 medium at 30°C and pH 7.2. This strain grows on different sources of plant-derived carbon and produces a wide range of enzymes. The actinomycete S331 strain was cultured on a CMS cellulose-based solid and liquid medium as the only carbon source. Screening of cellulolytic activity on a solid medium shows clear halos around the colonies. In addition, the enzymatic activity on ISP9 liquid-based cellulose medium is estimated at 10.08 IU/ml. The obtained results showed that: the maximum of cellulolytic activity is reached after 4 days and an optimum pH of 4. Moreover, cellulose and meat extract have been shown to be the best carbon and nitrogen sources respectively. After optimization, the cellulolytic activity was improved by a factor of 2.76 fold, ie 27.89 IU / ml. This activity remains competitive compared to those obtained in the genus Bacillus and Streptomyces.