Abstract:

The development of environmentally benign, biodegradable materials is considered an important way to address "white pollution". Importantly, organic acid is one of the crucial monomers for preparing biodegradable materials. In recent years, the synthesis of organic acids through green and efficient methods has attracted much attention. As the most promising carbon source recognized for renewability and affordability, lignocellulose is considered a promising carbon source for the biochemical industry. Converting lignocellulose into organic acid is critical to preparing biodegradable materials and achieving carbon neutrality, which meets the requirements of the green and sustainable development strategy. Hence, researchers are focusing their investigations on the lignocellulose biorefinery. To date, innovations in synthetic biology have significantly advanced organic acid manufacturing. For example, the yield of succinic acid has exceeded 150 g/L, which facilitates the formation and development of the bio-based biodegradable materials industry. In this paper, various lignocellulose pretreatment technologies were reviewed, including physical pretreatment, chemical pretreatment, biological pretreatment, physicochemical pretreatment, and other emerging pretreatment methods. To realize the goal of efficient utilization of lignocellulose, the refining processes of lignocellulose were also reviewed, including detoxification of inhibitors, reductive catalytic fractionation, consolidated bioprocessing, and other methods. After the pretreatment and refining process, lignocellulose is transformed to sugars and aromatic compounds, which can be utilized for producing various organic acid compounds, such as succinic acid, 3-hydroxypropionic acid, cis, cis-muconic acid, 2,5-furandicarboxylic acid, 2-pyrone-4, 6-dicarboxylic acid. Next, using the optimization of production of these organic acid compounds as examples, several synthetic biology strategies were summarized, including constructing biosynthetic pathways, optimizing regulatory elements, enlarging the substrates spectrum, and other strategies for improving cell production capacity. Finally, the development trends of the biodegradable materials industry are summarized and prospected. The development of emerging pretreatment and consolidated bioprocessing to facilitate the efficiency of lignocellulose utilization were discussed. Improving the robustness of microbial cell factories and designing the systematic lignocellulose conversion pathways could further optimize the performances of organic acid synthesis. The insights given in this review could facilitate further development on the industrial production of biodegradable materials, towards addressing the global energy crisis and "white pollution".

Key words: Lignocellulose, Organic acids, Bio-based materials, Green biomanufacturing

摘要：

开发环境友好型的生物可降解材料，被公认为是解决“白色污染”的重要途径。作为制备生物可降解材料的主要原料之一，有机酸的绿色高效制造备受关注。木质纤维素是储量庞大且可再生的自然资源，以木质纤维素为原料，通过生物转化的方式生产有机酸，是发展绿色可降解生物基材料的理想途径，具有过程绿色低碳的优势，符合建设绿色可持续发展经济和社会的需求。近年来，人们针对木质纤维素的生物炼制开展了大量研究，并在生物转化合成有机酸等领域取得了重要进展，特别是在高产有机酸微生物细胞工厂的设计开发上不断取得突破，使得生物基有机酸的生产水平屡创新高，丁二酸等品种的产量甚至突破了150 g/L，积极推动了生物基可降解材料产业的形成和发展。本文介绍了木质纤维素的组分并总结了木质纤维素的物理预处理法、化学预处理法、生物预处理法、物理-化学共处理法和化学-生物共处理法等多种预处理技术，以及抑制物的脱毒技术、还原催化分馏工艺、催化剂的回收以及偶联木质纤维素水解和发酵的制造工艺。其次，以木质纤维素为原料合成的高价值有机酸（丁二酸、3-羟基丙酸、粘康酸、2， 5-呋喃二甲酸和2-吡喃酮-4， 6-二羧酸）为例，从这些有机酸的生物合成途径，合成生物学改造策略和发酵条件优化等角度探讨了这些有机酸的研究现状。最后，对当前生物可降解材料产业链的发展趋势进行了总结和展望，讨论了开发新型预处理技术和优化联合生物处理工艺等策略对木质纤维素组分解离和利用的重要意义，并从提高微生物细胞工厂的鲁棒性以及设计木质纤维素的综合转化途径等方面进行系统分析，以期能为有机酸的工业化生产提供参考。

关键词: 木质纤维素, 有机酸, 生物基材料, 绿色生物制造