A novel strategy to enhance biohydrogen production using graphene oxide treated thermostable crude cellulase and sugarcane bagasse hydrolyzate under co-culture system.

Graphical abstract Improved production of crude enzyme by mean of mixed substrate of rice straw & orange peels in presence of graphene oxide and subsequent biohydrogen production using sugar cane bagasse hydrolyzate under co-cultivation system following dark fermentation. Highlights • Highly active cellulase is produced in presence of GO under fungal co-culture system. • GO treated crude enzyme shows long thermal and broad range pH stability. • High sugar (70.04 g/L) production is recorded in 14 h at 55 °C. • Sugar hydrolyzate is used for dark fermentative hydrogen production. • Cumulative hydrogen of 2870 ml/L with maximum production rate of 31.66 ml/L/h in 72 h. Abstract Graphene oxide (GO) treated thermostable crude cellulase has been obtained via fungal co-cultivation of strain Cladosporium cladosporioides NS2 and Emericella variecolor NS3 using mix substrate of orange peel and rice straw under solid state fermentation (SSF). Enzyme activity of 60 IU/gds FP, 300 IU/gds EG and 400 IU/gds BGL are recorded in the presence of 1.0% GO in 96 h. This crude enzyme showed 50 °C as optimum incubation temperature, thermally stable at 55 °C for 600 min and stability in the pH range 4.5–8.0. Further, 70.04 g/L of sugar hydrolyzate is obtained from enzymatic conversion of 3.0% alkali pre-treated baggase using GO treated crude cellulase. Finally, 2870 ml/L cumulative biohydrogen production having bacterial biomass ∼2.2 g/L and the complimentary initial pH 7.0 is recorded from sugar hydrolyzate via dark fermentation using co-culture of Clostridium pasteurianum (MTCC116) and a newly isolated Bacillus subtilis PF_1. [ABSTRACT FROM AUTHOR]