Wang Hanyu, Sun Tao, Zhao Zhen, Gu Shuying, Liu Qian, Wu Taju, Wang Depei, Tian Chaoguang, Li Jingen
College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.
National Technology Innovation Center of Synthetic Biology, Tianjin, China.
Front Microbiol. 2021 Apr 28;12:664011. doi: 10.3389/fmicb.2021.664011. eCollection 2021.
Efficient biological conversion of all sugars from lignocellulosic biomass is necessary for the cost-effective production of biofuels and commodity chemicals. Galactose is one of the most abundant sugar in many hemicelluloses, and it will be important to capture this carbon for an efficient bioconversion process of plant biomass. Thermophilic fungus has been used as a cell factory to produce biochemicals directly from renewable polysaccharides. In this study, we draw out the two native galactose utilization pathways, including the Leloir pathway and oxido-reductive pathway, and identify the significance and contribution of them, through transcriptional profiling analysis of and its mutants on galactose. We find that galactokinase was necessary for galactose transporter expression, and disruption of resulted in decreased galactose utilization. Through metabolic engineering, both galactokinase deletion and galactose transporter overexpression can activate internal the oxido-reductive pathway and improve the consumption rate of galactose. Finally, the heterologous galactose-degradation pathway, De Ley-Doudoroff (DLD) pathway, was successfully integrated into , and the consumption rate of galactose in the engineered strain was increased by 57%. Our study focuses on metabolic engineering for accelerating galactose utilization in a thermophilic fungus that will be beneficial for the rational design of fungal strains to produce biofuels and biochemicals from a variety of feedstocks with abundant galactose.
木质纤维素生物质中所有糖类的高效生物转化对于生物燃料和商品化学品的经济高效生产至关重要。半乳糖是许多半纤维素中含量最丰富的糖类之一，捕获这种碳对于植物生物质的高效生物转化过程至关重要。嗜热真菌已被用作细胞工厂，直接从可再生多糖生产生物化学品。在本研究中，我们通过对嗜热栖热菌及其半乳糖突变体进行转录谱分析，梳理出两条天然的半乳糖利用途径，包括Leloir途径和氧化还原途径，并确定它们的意义和贡献。我们发现半乳糖激酶对于半乳糖转运蛋白的表达是必需的，嗜热栖热菌的破坏导致半乳糖利用减少。通过代谢工程，半乳糖激酶缺失和半乳糖转运蛋白过表达均可激活内部氧化还原途径并提高半乳糖的消耗率。最后，将异源半乳糖降解途径，即De Ley-Doudoroff（DLD）途径成功整合到嗜热栖热菌中，工程菌株中半乳糖的消耗率提高了57%。我们的研究聚焦于代谢工程，以加速嗜热真菌中半乳糖的利用，这将有利于合理设计真菌菌株，以便从富含半乳糖的各种原料生产生物燃料和生物化学品。
