Second-generation or lignocellulosic biofuels are a tangible source of renewable energy, which is critical to combat climate change by reducing the carbon footprint. Filamentous fungi secrete cellulose-degrading enzymes called cellulases, which are used for production of lignocellulosic biofuels. However, inefficient production of cellulases is a major obstacle for industrial-scale production of second-generation biofuels. We used computational simulations to design and implement synthetic positive feedback loops to increase gene expression of a key transcription factor, CLR-2, that activates a large number of cellulases in a filamentous fungus, Neurospora crassa. Overexpression of CLR-2 reveals previously unappreciated roles of CLR-2 in lignocellulosic gene network, which enabled simultaneous induction of approximately 50% of 78 lignocellulosic degradation-related genes in our engineered Neurospora strains. This engineering results in dramatically increased cellulase activity due to cooperative orchestration of multiple enzymes involved in the cellulose degradation pathway. Our work provides a proof of principle in utilizing mathematical modeling and synthetic biology to improve the efficiency of cellulase synthesis for second-generation biofuel production.

中文翻译：

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具有正反馈环的合成基因网络可放大神经孢菌中的纤维素酶基因表达。

第二代或木质纤维素生物燃料是可再生能源的有形资源，对于通过减少碳足迹来应对气候变化至关重要。丝状真菌分泌称为纤维素酶的纤维素降解酶，用于生产木质纤维素生物燃料。然而，纤维素酶的低效率生产是第二代生物燃料的工业规模生产的主要障碍。我们使用计算仿真来设计和实施合成正反馈回路，以增加关键转录因子CLR-2的基因表达，该因子激活丝状真菌Neurospora crassa中的大量纤维素酶。。CLR-2的过表达揭示了CLR-2在木质纤维素基因网络中的作用，这在我们的工程化Neurospora菌株中能够同时诱导78种木质纤维素降解相关基因中的约50％。由于纤维素降解途径中涉及的多种酶的协同编排，该工程导致纤维素酶活性急剧增加。我们的工作提供了利用数学模型和合成生物学来提高纤维素酶合成用于第二代生物燃料生产的效率的原理证明。