A low-cost approach for the generation of enhanced sugars and ethanol from rice straw using in-house produced cellulase-hemicellulase consortium from A. niger P-19

A natural variant of Aspergillus niger P-19 was used for the in-house production of cellulase-hemicellulase consortium for efficient and low-cost saccharification of rice straw. Solid-state fermentation of raw rice straw produced the highest enzyme titers corresponding to 126, 36, 47, 693, and 57 IU/g for CMCase, FPase, β-glucosidase, xylanase, and mannanase after 5 days. The enzyme characterization revealed that all the components of the consortium had the optima at 60 °C and pH 4.0 and were highly stable at 50-60 °C for up to 408 h. The crude in-house enzyme preparation worked well in the saccharification of 0.25 N NaOH pretreated rice straw releasing 70 g/l of reducing sugars with 10% solid loading thus proving to be a low-cost approach for producing high titers of sugars. The fermentation of C6 sugars resulted in an ethanol yield of 15.6 g/l with scope for improving the yield by simultaneously targeting the C5 sugars. © 2020 Elsevier Ltd