Lignocellulose is the most abundant biomass on earth with an annual production of about 2 × 1011 tons. It is an inedible renewable carbonaceous resource that is very rich in pentose and hexose sugars. The ability of microorganisms to use lignocellulosic sugars can be exploited for the production of biofuels and chemicals, and their concurrent biotechnological processes could advantageously replace petrochemicals’ processes in a medium to long term, sustaining the emerging of a new economy based on bio-based products from renewable carbon sources. One of the major issues to reach this objective is to rewire the microbial metabolism to optimally configure conversion of these lignocellulosic-derived sugars into bio-based products in a sustainable and competitive manner. Systems’ metabolic engineering encompassing synthetic biology and evolutionary engineering appears to be the most promising scientific and technological approaches to meet this challenge. In this review, we examine the most recent advances and strategies to redesign natural and to implement non-natural pathways in microbial metabolic framework for the assimilation and conversion of pentose and hexose sugars derived from lignocellulosic material into industrial relevant chemical compounds leading to maximal yield, titer and productivity. These include glycolic, glutaric, mesaconic and 3,4-dihydroxybutyric acid as organic acids, monoethylene glycol, 1,4-butanediol and 1,2,4-butanetriol, as alcohols. We also discuss the big challenges that still remain to enable microbial processes to become industrially attractive and economically profitable.

中文翻译：

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从木质纤维素糖生产生物基化学品的工程微生物途径：现状和观点。

木质纤维素是地球上最丰富的生物质，年产量约为2×1011吨。它是一种不可食用的可再生碳质资源，富含戊糖和己糖。可以利用微生物使用木质纤维素糖的能力来生产生物燃料和化学品，并且它们的同时进行的生物技术过程可以在中长期内有利地替代石油化工的过程，从而维持基于生物产品的新经济的兴起来自可再生碳源。达到此目标的主要问题之一是重新连接微生物代谢，以可持续和竞争的方式优化配置这些木质纤维素衍生糖向生物基产品的转化。系统的代谢工程涵盖合成生物学和进化工程，似乎是应对这一挑战的最有前途的科学和技术方法。在这篇综述中，我们研究了在微生物代谢框架中重新设计天然和实施非天然途径的最新进展和策略，以将木质纤维素材料中的戊糖和己糖同化和转化为相关的工业化合物，从而获得最大的产量，滴度和生产率。这些包括乙醇酸，戊二酸，中康酸和3,4-二羟基丁酸作为有机酸，单乙二醇，1,4-丁二醇和1,2,4-丁三醇作为醇。我们还将讨论使微生物工艺变得具有工业吸引力和经济效益的巨大挑战。