Sugar beet is considered the second source of sugar production in the world, but ‎it becomes the first source in Egypt and several other countries all over the ‎world. The present study aimed to convert the agro-industrial beet pulp that ‎consists of cellulosic material into fermentable sugars as a friendly source of ‎energy. The cellulases producing bacteria and actinomycetes are associated with ‎beets' pulps and roots. The study also aimed to optimize the conditions of ‎cellulases production, e.g., incubation time, temperature and pH. One hundred ‎and two isolates of bacteria and actinomycetes were isolated from these samples ‎and then screened to determine their potency to produce cellulases. Seven isolates ‎were recorded as high producers (two from rhizospheres, one from endophytes, ‎and four from the beet pulp). These seven isolates were classified according to ‎morphological and biochemical tests as S11 (Streptomyces), S31 (Streptomyces), ‎S45 (Bacillus), and S72 (Bacillus), S73 (Streptomyces), S85 (Streptococcus) and ‎S88 (Bacillus). Optimization for the incubation period, temperature, and pH ‎showed that activities of the highest three tested isolates S11, S45, and S88 were ‎‎0.73, 0.17, and 0.54 U/ml after two days of the incubation period. These levels ‎increased to 1.33, 0.24 and 0.76 U/ml on the fourth incubation day at different ‎temperatures and pH degrees. According to the results, it is recommended to use ‎bacteria (Streptomyces), which is sample No. S11 isolated from the rhizosphere ‎soil of beetroots was the high producer of cellulases at 50°C and pH 7.‎