Bioconversion of rice husk to sugar by crude cellulase complex of a novel Aspergillus protuberus for cellulosic ethanol production using response surface methodology

The extensive usage of fossil fuels worldwide urges the generation of renewable energy like biofuels from biological waste. The multifaceted perspective for production of ethanol on rice husk was selected following three unique steps: (i) first step was statistical standardization of cellulase production by a novel fungus Aspergillus protuberus through rice husk fermentation, (ii) second phase included saccharification of pretreated rice husk with enzyme for maximum titer of reducing sugar, and (iii) at last statistical standardization for transformation of sugar into ethanol with fermentation using Saccharomyces cerevisiae was done. Enzyme loading at a rate of 40 U/g yielded higher reducing sugar (i.e. 24 g/L) from NaOH treated rice husk. Throughout ethanol fermentation, dilute NaOH remains a key component to trigger production of ethanol (7.54 g/l), representing the persistent influence of the perpetrator strains. In this investigation, without additional nutrients to the fermentation medium and non-detoxified pre-treated rice husk were used. Size of the inoculums and pore volume of the pretreated husk improved the fungal fermentation. Nevertheless, bioethanol provides several advantages like renewability, biodegradability, and also place an important role in reducing greenhouse gas emissions. Certainly, this study opens up new avenues in the sustainable production of cellulosic ethanol.