Integrating genetic-engineered cellulose nanofibrils of rice straw with mild chemical treatments for enhanced bioethanol conversion and bioaerogels production

Abstract

Cellulose in crop straws represents an abundant biopolymer convertible for biofuels and bioproducts, while the inherent recalcitrance of lignocellulose limits these applications. By selecting desirable rice mutant (cesa7) from site-mutation of the OsCESA7 isoform essential for cellulose biosynthesis, this study examined much improved lignocellulose recalcitrance such as reduced cellulose crystallinity, polymerization and nanofibril length for increased lignocellulose porosity and accessibility. Compared with its wild type, the cesa7 mutant showed a near-complete biomass saccharification with hexose yields of over 96% (% cellulose) for bioethanol production raised by 58%− 71% under three green-like pretreatments performed. Meanwhile, the cellulose substrate of cesa7 mutant was applied to produce aerogels with high porosity and large specific surface under less-intensity ultrasonic treatment, and its further mild chemical modification led to significantly raised oil adsorption capacity by 55%, mainly due to higher proportion of nanofibrils and the honeycomb-like fibers structure observed. It has thus provided an applicable approach for high-yield bioethanol and high-quality aerogels by integrating genetic-modified cellulose substrates with cost-effective process technology.