Production and optimization of high grade cellulase from waste date seeds by Cellulomonas uda NCIM 2353 for biohydrogen production

Production of high grade cellulolytic enzymes from waste agricultural biomass would valorise these wastes to valuable products as well as avoid the pollution problems associated with landfilling of the biomass. In the present study, waste date palm (Phoenix dactylifera) seeds were valorised for cellulase production from Cellulomonas uda NCIM 2353 and for its subsequent usage in biohydrogen production. Optimization of key operational parameters such as date seed concentration, xylose, casein and initial media pH were performed using central composite design to obtain the maximum enzyme yield. The optimum values obtained were (g/L): date seed concentration 30.65, xylose concentration 0.55, casein 7.00 and pH 7.40 for a determination coefficient of 0.999. The results demonstrated a higher prediction accuracy of response surface methodology as the cellulase activity increased six fold (175.96 IU/mL) after optimization. The optimum pH and temperature of purified cellulase was 7 and 50 degrees C respectively where the enzyme retained nearly 80% of activity upto 180 min. Enzymatic hydrolysis studies showed that a high saccharification efficiency of 60.5% was obtained for acid pretreated sugarcane bagasse by the indigenous cellulase, equivalent to the performance of commercial cellulase. Further, the as-obtained reducing sugars were decomposed by Clostridium thermocellum to produce biohydrogen of maximum concentration 187.44 mmol/L at end of 24 h of fermentation. Results show that date seed substrate based cellulase protein can be employed for industrial processes of biohydrogen production. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.