Increased consumption of fossil fuels is an emerging problem. Scientists look for the existence of other alternatives to fossil fuels, including so-called renewable energy. Accordingly, we report the production of bio-ethanol from the remnants of castor oil bean seed cake (CBC) by the carboxymethylcellulase enzyme (CMCase). A bacterial strain isolated from rice straw showing higher CMCase activity was identified. The 16S rRNA result showed a 93% homology with the 16SrRNA gene sequences of Pseudomonas poae RE∗1-1-14, the strain was identified as Pseudomonas poae AB3. In addition, our results showed that the highest enzyme activity was achieved after 48 h and inoculum size of 3.7 × 105 CFU. The optimum temperature, pH and Carboxymethylcellulose (CMC) concentration for the highest enzyme activity was 25 °C, pH 7 and 10 g/l respectively. Furthermore, The CMCase was purified by ammonium sulphate at a concentration of 60%. The SDS-PAGE of the purified enzyme showed a molecular weight of 88 kDa. Additionally, the (CBC) was hydrolyzed by the purified CMCase at the enzyme optimum conditions. The results showed the liberation of 5.2 g/L of reducing sugar by using dinitrosalicylic acid (DNS) assay. Finally, the total sugar produces 35 g/L after 48 h when Saccharomyces cerevisiae was used as a fermentation agent. Hence for the first time, we have been successfully able to produce bioethanol from CBC with CMCase of Pseudomonas poae.
Keywords: Bioethanol; Carboxymethylcellulase; Castor bean cacke; Pseudomonas poae.