Abstract

In the pursuit of sustainable development, there is a rapid increase in the generation of biodiesel, which eventually results in the synthesis of glycerol as a major by-product. The surplus amount of glycerol from biodiesel industries is one of the rising environmental concerns. Alternatively, glycerol can serve as an attractive raw material for synthesizing value-added products that offer simultaneous management and valorization of this waste. 1,3-propanediol is a vital value-added material having extensive applications in the industrial domain. Microbial biosynthesis of 1,3-propanediol from glycerol has proven to be an economic and eco-friendly approach. However, biosynthesis of this bio-product is often affected by some environmental stresses, such as glycerol and 1,3-propanediol concentrations, accumulation of 3-hydroxypropionaldehyde, and by-product synthesis. To overcome the influences of these factors as well as to improve 1,3-propanediol yield, efforts have been devoted over the past years, which mostly included the application of metabolic engineering strategies to transform microbial strains into robust cell factories. This review focuses on the environmental stresses restricting 1,3-propanediol biosynthesis, and how these restrictions could be overcome using the metabolic engineering strategies. In this context, some technological and strategical aspects, including rechanneling metabolic flux in co-producing strains, rebalancing of co-factors and gene expression, co-culture and co-substrate fermentation, and application of untranslated region engineering. It also discusses the role of key enzymes involved in 1,3-propanediol biosynthesis and the influence of polyhydroxyalkanoate granule-associated protein on the tolerance to high concentration of this bio-product.

Graphic abstract

中文翻译：

---

甘油1,3-丙二醇生物制造的最新技术和战略发展

摘要

为了追求可持续发展，生物柴油的产生迅速增加，最终导致甘油作为主要副产物的合成。来自生物柴油工业的甘油的过量是日益关注的环境问题之一。另外，甘油可以用作合成增值产品的诱人原料，这些增值产品可以同时管理和评估这种废物。1,3-丙二醇是一种至关重要的增值材料，在工业领域具有广泛的应用。从甘油微生物合成1，3-丙二醇已被证明是一种经济，环保的方法。但是，这种生物产品的生物合成通常会受到一些环境压力的影响，例如甘油和1,3-丙二醇的浓度，3-羟基丙醛的积累，和副产物合成。为了克服这些因素的影响以及提高1,3-丙二醇的产量，过去几年来一直在努力，其中主要包括应用代谢工程策略将微生物菌株转化为坚固的细胞工厂。这篇综述的重点是限制1,3-丙二醇生物合成的环境压力，以及如何使用代谢工程策略克服这些限制。在这种情况下，一些技术和战略方面，包括重新引导共同生产菌株中的代谢通量，重新平衡辅助因子和基因表达，共同培养和共同底物发酵以及未翻译区域工程的应用。它还讨论了与1相关的关键酶的作用

图形摘要