Characterization Of The OsCesa9-edited Rice Mutant That Is Applicable For High Biomass Enzymatic Saccahrification And Biochar Production

Rice straw provides large amounts of lignocellulose residues convertible for biofuels and biomaterials,which could not only avoid air pollution from straw burning,but also create the economic benefit.Crop straw is rich at lignocellulose,but lignocellulose recalcitrance decides a costly biomass process unacceptable for biofuel production.Although physical and chemical pretreatment is effective to reduce lignocellulose recalcitrance,it requires strong conditions with potential secondary waste release into the environment.Hence,genetic modification of plant cell walls has been considered as a promising solution for cost-effective and green-like biomass process.In this study,we collected two rice mutants(cesa9-1、cesa9-2)generated from gene-editing system,and determined their cell wall composition and cellulose features.We then performed Cao pretreatments with mature straws,and examined much enhanced biomass enzymatic saccharification and bioethanol production in the mutant compared to the wild type(NPB).Finally,we generated biochar from thermochemical conversion with the mature straws,and detected that the rice mutant was of higher adsorption capacity with Congo red dye relative to the NPB.The main results were described below:1.Compared to the NPB,the cesa9-1 mutant showed less cellulose level by 16% and more hemicellulose content by 15% in their mature straws,and raised lignin contents by 16%,but its cellulose Cr I is reduced by 12% and both crude and crystalline cellulose DP values are respectively decreased by 11% and 32%.Meanwhile,the cesa9-2 mutant is of reduced cellulose level by 29% and raised hemicellulose contents by 8%,and it also shows slightly reduced cellulose Cr I by 7% with much reduced cellulose DP values by 16% and 39% relative to the NPB.2.Under Ca O pretreatments with mature straws,the cesa9-2 mutant shows biomass enzymatic saccharification raised by 54%,bioethanol yield raised from 14.7% to 16.4% and sugar-ethanol conversion rate raised from 92.1% to 97.6%,compared to the NPB.3.By performing thermochemical conversion with the mature straws of the cesa9-1 mutant and NPB,this study generated two biochar samples and measured their optimal adsorption with Congo red dye under relatively higher incubation temperature,lower p H value and longer reaction time.4.Both biochar samples of NPB and cesa9-1 mutant exhibited a typical single-molecularlayer adsorption,but chemical adsorption plays a leading role.The activated biochar sample of cesa9-1 mutant shows much improved adsorption performance,and the maximum adsorption capacity with Congo red dye is raised from 80.9717 mg / g to 86.5052 mg / g.In conclusion,the rice mutant selected from gene-editing technology has showed normal plant growth to remain biomass yields,and has also exhibited much improved lignocellulose recalcitrance in the mature straw for remarkably enhanced biomass enzymatic saccharification towards higher bioethanol production compared to the NPB.Meanwhile,the rice mutant is favor for generation of biochar that is of high adsorption capacity with chemical dye.Therefore,this study has provided a novel strategy for costeffective biofuels and value-added biochar by integrating genetic lignocellulose modification with green-like biomass processing.