In recent years, the increasingly serious and clear effects of climate change have increased interest in renewable fuels and platform chemicals. Microbial platforms that can produce these compounds in an economically efficient way have emerged as an attractive alternative to the traditional production approaches. Here, we engineered the industrially-relevant yeast Pichia pastoris to produce the platform chemical 3-methyl-1-butanol (3M1B, isopentanol) directly from the renewable carbon source glucose. Specifically, we overexpressed the endogenous valine and leucine biosynthetic pathways to increase the production of the key pathway intermediate, 2-ketoisocaproate (2-KIC). Overexpression of the artificial keto-acid degradation pathway converted 2-KIC into 3M1B. Down-regulation of the side-product ethanol production using the CRISPR/Cas9 system led to a strain that is able to produce 3M1B at a titer of 191.0 ± 9.6 mg/L, the highest titer reported to date in a non-conventional yeast. We envision that our yeast system will pave the way for an efficient production system for this important class of platform compounds.

中文翻译：

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毕赤酵母代谢工程生产异戊醇（3-甲基-1-丁醇）

近年来，气候变化日益严重和明显的影响增加了对可再生燃料和平台化学品的兴趣。能够以经济有效的方式生产这些化合物的微生物平台已成为传统生产方法的有吸引力的替代方案。在这里，我们设计了工业相关酵母毕赤酵母，以直接从可再生碳源葡萄糖生产平台化学物质 3-甲基-1-丁醇（3M1B，异戊醇）。具体来说，我们过表达内源性缬氨酸和亮氨酸生物合成途径，以增加关键途径中间体 2-酮异己酸 (2-KIC) 的产量。人工酮酸降解途径的过度表达将 2-KIC 转化为 3M1B。使用 CRISPR/Cas9 系统下调副产物乙醇生产导致菌株能够以 191.0 ± 9.6 mg/L 的滴度生产 3M1B，这是迄今为止在非常规酵母中报道的最高滴度。我们设想我们的酵母系统将为此类重要平台化合物的高效生产系统铺平道路。