转化纤维素合成PHA的鞘氨醇杆菌设计构建研究

以生物可降解塑料聚羟基脂肪酸(PHA)替代传统石油基塑料的主要瓶颈在于PHA的生产成本居高不下。本项目拟设计构建一个能利用纤维素原料合成PHA的微生物细胞工厂，实现聚羟基庚酸(P3HHp)的高效生物合成。首先，利用能高效降解纤维素的鞘氨醇杆菌，采用合成生物学和代谢工程技术，外源引入脂肪酸合成途径，使细胞高效生产庚酸。其次，通过外源引入PHA聚合酶等构建聚羟基脂肪酸合成通路，完成原料降解和产物合成双功能的整合，使鞘氨醇杆菌获得“一步发酵法”转化纤维素为聚3-羟基庚酸的能力。最后，通过动态分析优化P3HHp的生产条件，提高转化率。研究成果可为建立和发展生物质原料利用的新策略提供科学基础，同时有助于丰富和发展生物高分子材料生产的创新技术体系。

High production cost of the bioplastic polyhydroxyalkanoates (PHA) is a major obstacle to replace traditional petro-based plastics. In this study, we will construct a microbial cell factory to produce poly-3-hydroxyheptanoate (P3HHp) using cellulose as the starting substrate. First, based on the high efficiency degradation capability, exogenous fatty acid synthesis pathway will be introduced into a Sphingobacterium strain for utilization of cellulose to produce heptanoic acid. Then, the exogenous PHA synthase will be introduced to realize the bifunctional integration of substrate transformation and product synthesis in one cell. The constructed bacterial manufacturing system will execute the conversion of cellulose to the product PHA by "one-step" fermentation. Finally, analysis of the dynamic metabolic processes will be performed for optimization of the P3HHp production. This study will provide the development of new strategies for the efficient conversion of the natural lignocellulose available and develop an effective system for microbial synthesis of biodegradable plastics.