近日，生物質與生物能源團隊在國際綠色化學領域權威期刊Green Chemistry在線發表了題為Distinct cellulose nanofibrils generated for improved Pickering emulsions and lignocellulose-degradation enzymes secretion coupled with high bioethanol production in natural rice mutant的研究論文，在國際高分子化學領域權威期刊Carbohydrate Polymers刊發了題為Insights into pectin dominated enhancements for elimination of toxic Cd and dye coupled with ethanol production in desirable lignocelluloses的研究論文。這兩項研究利用優質水稻天然突變體，發現纖維素納米結構缺陷增強功能材料特性的微觀機理，解析果膠糖醛酸去除重金屬和化工污染的作用機制，并構建稭稈纖維乙醇聯産高值生物材料技術體系，從而開辟基于遺傳背景的農業廢棄物綠色高效利用的新路徑。

農作物稭稈蘊含豐富的生物質資源，降解轉化為“零碳”生物能源和高值生物制品，可助力我國“雙碳”目标實現，促進農業可持續發展和現代農業産業鍊延長。然而，植物細胞壁天然抗降解屏障制約了生物質的全面綜合利用，遺傳改良細胞壁結構，可從源頭解決農作物稭稈高值利用效率低、成本高、易二次污染的瓶頸問題。纖維素納米纖維（CNF）因其納米尺寸和界面效應，具有比表面積大、穩定性強、分散性好和反應活性高等優勢，但其制備工藝能耗高或存在化學污染，限制了CNF的大規模應用。本研究發現，與普通水稻相比，天然水稻細胞壁突變體（Osfc16）稭稈的直接酶解效率顯著提高37%，纖維乙醇産率顯著提高19%，具有抗降解屏障降低的優良特性。同時，在更少循環次數的高壓均質工藝下，酶解殘渣中産生的CNF，其液滴粒徑更小、界面活性更高，改善了皮克林乳化劑的乳液性能和儲存穩定性。此外，還發現低劑量的CNF可以作為裡氏木黴分泌纖維素酶複合物的有效誘導劑，誘導酶的蛋白質産量提高99%，内切葡聚糖酶和木聚糖酶活性分别提高27%和51%。該研究揭示了由低抗性木質纖維素産生新型CNF的多重作用，為充分利用生物質生産具有成本效益的生物乙醇和高價值的生物産品提供了一種綠色新型技術（Green Chemistry, 2022, DOI:10.1039/D1GC04447H）。

圖1 水稻天然突變體纖維素納米纖維作為皮克林乳化穩定劑與産酶誘導劑聯産纖維乙醇模型圖

果膠是一類富含半乳糖醛酸的細胞壁多糖，具有豐富的活性基團，對重金屬和化學染料具有潛在的吸附性能。本研究發現，重金屬镉（Cd）脅迫激活細胞壁網絡動态調節，促進果膠在細胞壁中的沉積，而天然水稻細胞壁突變體（Osfc16）表現出更強的去甲酯化半乳糖醛酸積累能力和微量Cd富集能力。同時，重金屬使細胞壁産生結構缺陷，進一步降低了細胞壁的抗降解性，顯著增強生物質酶解糖化效率和生物乙醇産率，并且生物質的預處理工藝能夠同步提取回收90%的Cd。利用果膠的特性，從富含果膠的柑橘皮中提取糖醛酸，與乙醇發酵殘渣進行化學交聯，生成一種同時吸附Cd和亞甲基藍（MB）的增強型生物吸附劑。該研究闡明了果膠在Cd和MB吸附以及生物質酶促糖化中的多重作用機制，為農田重金屬和化工染料的減污修複，植物修複收獲物的無害化處理，農業廢棄物的增值利用和重金屬的回收處置，提供了新思路（Carbohydrate Polymers, 2022, 286:119298）。

圖2 果膠在Cd和MB吸附以及生物質酶促糖化中的多重作用模型圖

我院生物質能團隊王豔婷高級工程師為兩篇文章的通訊作者，博士生彭昊和趙雯悅碩士為Green Chemistry的共同第一作者，博士生餘華為Carbohydrate Polymers第一作者，團隊彭良才教授、夏濤副教授、食科院劉石林教授、理學院王運教授、湖北文理學院餘海忠教授等參與研究。

王豔婷，77779193永利官网高級工程師，主要從事植物細胞壁遺傳改良與生物質降解轉化相關工作，現主持國家自然科學基金（No. 32101701）和中央高校創新基金（No. 2662020ZKPY013）等項目。近年來，以第一或通訊作者在植物細胞壁基本特征結構模型（中國科學▪生命科學，2014）；果膠糖醛酸調控水稻稭稈高效降解機制（Bioresource Technology, 2015）；遺傳改良植物細胞壁增強能源作物生物質産量與生物能源産率（Biotechnology Advances, 2016）；原位觀測細胞壁多糖酶促水解動态（Carbohydrate Polymers, 2018）；能源植物纖維素納米纖維制備食品級皮克林乳液穩定劑（Food Hydrocolloids, 2019）；量子點熒光免疫标記預處理下不同細胞壁聚合物的同步解聚（Talanta, 2020）；經濟作物木質纖維素高效酶促糖化機制（Molecules, 2021）；能源作物細胞壁遺傳改良、微生物基因工程改造和生物質綠色加工的多學科交叉融合研究（Renewable and Sustainable Energy Reviews, 2021）等方面取得了系統性進展，并受邀在國内外知名綜述期刊發表多篇研究型綜述。共發表SCI論文50餘篇，總引用次數超過1600次，H指數22。

Green Chemistry摘要：

Although lignocellulose represents enormous and sustainable biomass resource convertible for biofuels and bioproducts, the green-like and cost-effective technology is increasingly considered to generate value-added bioproducts along with biofuel production. Herein, this study took advantage of the natural rice mutant (Osfc16) that is of recalcitrance-reduced lignocellulose, and performed a direct enzymatic hydrolysis of rice straw to achieve significantly raised bioethanol yield by 19% at p < 0.01, compared with wild type. Meanwhile, this work generated optimal cellulose nanofibrils (CNFs) from the remaining enzymatic residues under much less cycles of high-pressure homogenization. Notably, due to their characteristic surfaces, the CNFs at low dosage could not only act as the effective inducer for T. reesei secretion of cellulases complexes with significantly raised protein yields by 99% and enzymes (endoglucanases and xylanases) activities by 27% and 51% by using full rice straw as carbon source, but also play a more efficient stabilizer role for improving almost all major parameters of Pickering emulsions including emulsion index, droplet size, interfacial tension, zeta potential, water holding capacity and storage condition, compared to other chemical inducers and stabilizers (CNFs, proteins, starch) that have been applied in previous studies. Hence, this study has proposed a mechanism model to elucidate why the desirable rice mutant enables to generate the distinct CNFs that are favor for Pickering emulsions stabilization and mixed-cellulases induction coupled with relatively low-cost bioethanol production, providing multiple non-chemical processes as novel green-like technology for complete biomass utilization towards low-cost bioethanol production and high-value bioproducts.

原文鍊接：

https://pubs.rsc.org/en/content/articlepdf/2022/GC/D1GC04447H

Carbohydrate Polymers摘要：

Pectin is a minor wall polysaccharide with potential applications for bioproducts. Despite the application of specific plants and biomass-based sorbents for environmental remediation, little has been reported about characteristic roles of pectin. Using the natural rice mutant (Osfc16) treated with Cd, this study explored that pectin could predominately enhance Cd accumulation with lignocellulose, mainly due to remarkably raised uronic acids deposition. The Cd-treatment further reduced lignocellulose recalcitrance for significantly enhanced biomass saccharification and bioethanol production along with almost complete Cd release. Using all remaining fermentation rice residues that are of typical ribbon-structure and large surface, this study generated novel biosorbents by optimal chemical oxidation with the pectin extraction from citrus peels, and examined consistently raised Cd and methylene blue (MB) adsorption capacities. Therefore, this work has proposed a mechanism model about multiple pectin enrichment roles for Cd and MB removals in agricultural and industry locations with full lignocellulose utilization towards bioethanol production.

原文鍊接：

https://www.sciencedirect.com/science/article/pii/S0144861722002028

文字：彭昊、餘華

審核：王豔婷