Anaerobic fermentation of glycerol by Escherichia coli:: A new platform for metabolic engineering
Anaerobic fermentation of glycerol by Escherichia coli:: A new platform for metabolic engineering
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DOI：
10.1002/bit.21025
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发表时间：
2006-08-05
影响因子：
3.8
通讯作者：
Gonzalez, Ramon
中科院分区：
文献类型：
--
作者：
Dharmadi, Yandi;Murarka, Abhishek;Gonzalez, Ramon
作为生物柴油燃料和油脂化工生产的不可避免的副产品，全球甘油过剩导致传统的甘油生产/精炼工厂关闭，需要对这种现在丰富的碳源进行新的应用。在这篇文章中，我们报告了我们的发现，大肠杆菌可以以一种依赖于pH的方式发酵甘油。我们假设甘油发酵与二氧化碳的可获得性有关，在酸性条件下，二氧化碳是由甲酸酸氢裂解酶(FHL)氧化甲酸盐产生的。与这一假说一致，甘油发酵因阻断FHL的活性而受到严重损害。我们证明，与二氧化碳不同，氢(FHL介导的甲酸盐氧化的另一种产物)对细胞生长和甘油发酵有负面影响。此外，添加二氧化碳部分恢复了FHL缺乏菌株发酵甘油的能力。高pH导致低CO2产生(FHL活性低)和利用率(大部分CO2被转化为重碳酸盐)，从而导致甘油发酵非常低效。发酵后的甘油大部分以乙醇和琥珀酸的还原化合物形式回收(占产品混合物的93%)，这反映了甘油的高度还原状态，证实了该工艺的发酵性质。由于甘油是一种廉价、丰富和高还原碳源，我们的发现应该能够开发一个基于大肠杆菌的平台，用于从甘油厌氧生产还原化学物质，其产量高于从普通糖(如葡萄糖)获得的产量。(C)2006年威利期刊公司。
The worldwide surplus of glycerol generated as inevitable byproduct of biodiesel fuel and oleochemical production is resulting in the shutdown of traditional glycerol-producing/refining plants and new applications are needed for this now abundant carbon source. In this article we report our finding that Escherichia coli can ferment glycerol in a pH-dependent manner. We hypothesize that glycerol fermentation is linked to the availability Of CO2, which under acidic conditions is produced by the oxidation of formate by the enzyme formate hydrogen lyase (FHL). In agreement with this hypothesis, glycerol fermentation was severely impaired by blocking the activity of FHL. We demonstrated that, unlike CO2, hydrogen (the other product of FHL-mediated formate oxidation) had a negative impact on cell growth and glycerol fermentation. In addition, supplementation of the medium with CO2 partially restored the ability of an FHL-deficient strain to ferment glycerol. High pH resulted in low CO2 generation (low activity of FHL) and availability (Most CO2 is converted to bicarbonate), and consequently very inefficient fermentation of glycerol. Most of the fermented glycerol was recovered in the reduced compounds ethanol and succinate (93% of the product mixture), which reflects the highly reduced state of glycerol and confirms the fermentative nature of this process. Since glycerol is a cheap, abundant, and highy reduced carbon source, our findings should enable the development of an E. coli-based platform for the anaerobic production of reduced chemicals from glycerol at yields higher than those obtained from common sugars, such as glucose. (c) 2006 Wiley Periodicals, Inc.