Microbial production of short-chain alkanes
Microbial production of short-chain alkanes
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DOI：
10.1038/nature12536
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发表时间：
2013-10-24
期刊：
影响因子：
64.8
通讯作者：
Lee, Sang Yup
中科院分区：
文献类型：
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作者：
Choi, Yong Jun;Lee, Sang Yup
对有限的化石燃料和全球环境问题的日益关注使人们关注从可再生资源开发可持续生物燃料的必要性。虽然已经报道了微生物生产柴油的情况，但另一种需求量很大的运输燃料汽油的生产尚未得到证实。在这里，我们报告了平台大肠杆菌菌株的发展，这些菌株能够通过脂肪酰基（酰基载体蛋白（ACP））-脂肪酸-脂肪酰基辅酶A途径产生短链烷烃（SCA;汽油）、游离脂肪酸（FFA）、脂肪酯和脂肪醇。首先，通过删除fadE基因阻断β-氧化途径，以防止体内产生的脂肪酰辅酶A降解。为了增加适于随后在体内转化为SCA的短链脂肪酸的形成，通过缺失fadR基因来增强3-氧代酰基-ACP合酶（FabH）（1）（其被不饱和脂肪酰基-ACP（2）抑制）的活性以促进脂肪酸生物合成的起始; fadR基因的缺失阻止了负责不饱和脂肪酸生物合成的fabA和fabB基因的上调（3）。用硫酯酶（4）将短链脂肪酰基-ACP转化为相应的FFA，然后通过E.大肠杆菌脂肪酰辅酶A合成酶、丙酮丁醇梭菌脂肪酰辅酶A还原酶和拟南芥脂肪醛脱羰基酶。最终的工程菌株产生高达580.8 mg l（-1）的SCA，其由壬烷（327.8 mg l（-1））、十二烷（136.5 mg l（-1））、十三烷（64.8 mg l（-1））、2-甲基-十二烷（42.8 mg l（-1））和十四烷（8.9 mg l（-1））以及少量的其它烃组成。此外，该平台菌株可以使用fadD缺失的菌株生产短链FFA，并且通过引入不动杆菌属ADP 1蜡酯合酶（atfA）（5）和E.大肠杆菌突变型乙醇脱氢酶（adhE（mut））（6）。
Increasing concerns about limited fossil fuels and global environmental problems have focused attention on the need to develop sustainable biofuels from renewable resources. Although microbial production of diesel has been reported, production of another much in demand transport fuel, petrol (gasoline), has not yet been demonstrated. Here we report the development of platform Escherichia coli strains that are capable of producing short-chain alkanes (SCAs; petrol), free fatty acids (FFAs), fatty esters and fatty alcohols through the fatty acyl (acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA pathway. First, the beta-oxidation pathway was blocked by deleting the fadE gene to prevent the degradation of fatty acyl-CoAs generated in vivo. To increase the formation of short-chain fatty acids suitable for subsequent conversion to SCAs in vivo, the activity of 3-oxoacyl-ACP synthase (FabH)(1), which is inhibited by unsaturated fatty acyl-ACPs(2), was enhanced to promote the initiation of fatty acid biosynthesis by deleting the fadR gene; deletion of the fadR gene prevents upregulation of the fabA and fabB genes responsible for unsaturated fatty acids biosynthesis(3). A modified thioesterase(4) was used to convert short-chain fatty acyl-ACPs to the corresponding FFAs, which were then converted to SCAs by the sequential reactions of E. coli fatty acyl-CoA synthetase, Clostridium acetobutylicum fatty acyl-CoA reductase and Arabidopsis thaliana fatty aldehyde decarbonylase. The final engineered strain produced up to 580.8 mg l(-1) of SCAs consisting of nonane (327.8 mg l(-1)), dodecane (136.5 mg l(-1)), tridecane (64.8 mg l(-1)), 2-methyl-dodecane (42.8 mg l(-1)) and tetradecane (8.9 mg l(-1)), together with small amounts of other hydrocarbons. Furthermore, this platform strain could produce short-chain FFAs using a fadD-deleted strain, and short-chain fatty esters by introducing the Acinetobacter sp. ADP1 wax ester synthase (atfA)(5) and the E. coli mutant alcohol dehydrogenase (adhE(mut))(6).