Development of the bioeconomy is driven by our ability to access the energy-rich carbon trapped in recalcitrant plant materials. Current strategies to release this carbon rely on expensive enzyme cocktails and physicochemical pretreatment, producing inhibitory compounds that hinder subsequent microbial bioproduction. Anaerobic fungi are an appealing solution as they hydrolyze crude, untreated biomass at ambient conditions into sugars that can be converted into value-added products by partner organisms. However, some carbon is lost to anaerobic fungal fermentation products. To improve efficiency and recapture this lost carbon, we built a two-stage bioprocessing system pairing the anaerobic fungus Piromyces indianae with the yeast Kluyveromyces marxianus, which grows on a wide range of sugars and fermentation products. In doing so we produce fine and commodity chemicals directly from untreated lignocellulose. P. indianae efficiently hydrolyzed substrates such as corn stover and poplar to generate sugars, fermentation acids, and ethanol, which K. marxianus consumed while producing 2.4 g/L ethyl acetate. An engineered strain of K. marxianus was also able to produce 550 mg/L 2-phenylethanol and 150 mg/L isoamyl alcohol from P. indianae hydrolyzed lignocellulosic biomass. Despite the use of crude untreated plant material, production yields were comparable to optimized rich yeast media due to the use of all available carbon including organic acids, which formed up to 97% of free carbon in the fungal hydrolysate. This work demonstrates that anaerobic fungal pretreatment of lignocellulose can sustain the production of fine chemicals at high efficiency by partnering organisms with broad substrate versatility.

中文翻译：

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厌氧真菌水解木质纤维素产生游离糖和有机酸，用于马克斯克鲁维酵母的两阶段精细化工生产

生物经济的发展是由我们获取被困在顽固植物材料中的富含能量的碳的能力所驱动的。目前释放这种碳的策略依赖于昂贵的酶混合物和物理化学预处理，产生阻碍后续微生物生物生产的抑制性化合物。厌氧真菌是一种吸引人的解决方案，因为它们在环境条件下将未经处理的粗生物质水解成糖，这些糖可以被伙伴生物转化为增值产品。然而，一些碳损失到厌氧真菌发酵产物中。为了提高效率并重新捕获这些损失的碳，我们构建了一个两阶段生物处理系统，将厌氧真菌Piromyces indianae与酵母Kluyveromyces marxianus 配对，它生长在各种各样的糖和发酵产品上。在此过程中，我们直接使用未经处理的木质纤维素生产精细和商品化学品。磷。indianae有效水解玉米秸秆和杨树等底物，生成糖、发酵酸和乙醇，其中K . marxianus在生产 2.4 g/L 乙酸乙酯时消耗。K的工程菌株。marxianus还能够从P中生产 550 mg/L 的 2-苯基乙醇和 150 mg/L 的异戊醇。印第安亚科水解的木质纤维素生物质。尽管使用了未经处理的粗植物材料，但由于使用了包括有机酸在内的所有可用碳，其产量与优化的富酵母培养基相当，有机酸在真菌水解物中形成了高达 97% 的游离碳。这项工作表明，木质纤维素的厌氧真菌预处理可以通过与具有广泛底物多功能性的生物体合作来维持高效精细化学品的生产。