Synthesis of Methyl Halides from Biomass Using Engineered Microbes
Synthesis of Methyl Halides from Biomass Using Engineered Microbes
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DOI：
10.1021/ja809461u
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发表时间：
2009-05-13
影响因子：
15
通讯作者：
Voigt, Christopher A.
中科院分区：
文献类型：
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作者：
Bayer, Travis S.;Widmaier, Daniel M.;Voigt, Christopher A.
卤甲烷被用作农业熏蒸剂，是可以催化转化为化学品和燃料的前体分子。植物和微生物天然产生卤代甲烷，但这些生物产生的产量非常低或不适合工业生产。一个单一的甲基卤转移酶（MHT）将甲基从普遍存在的代谢产物S-腺苷甲硫氨酸（SAM）转移到卤离子。使用合成宏基因组学方法，我们化学合成了NCBI序列数据库中存在的所有89个来自植物、真菌、细菌和未鉴定生物体的推定MHT基因。在大肠杆菌中筛选该组以鉴定CH 3Cl、CH 3Br和CH 3 I产生的速率，其中56%的文库对氯化物有活性，85%对溴化物有活性，69%对碘化物有活性。在酿酒酵母中表达最高活性的MHT和随后的工程改造导致葡萄糖和蔗糖的生产率为190 mg/L-h。使用工程酵母和纤维素分解细菌Actinotalea fermentans的共生共培养物，我们能够从未加工的柳枝稷（Panicum virgatum），玉米秸秆，甘蔗渣和白杨（Populus sp.）中生产卤甲烷。这些结果表明，从非粮食农业资源生产卤代甲烷的潜力。
Methyl halides are used as agricultural fumigants and are precursor molecules that can be catalytically converted to chemicals and fuels. Plants and microorganisms naturally produce methyl halides, but these organisms produce very low yields or are not amenable to industrial production. A single methyl halide transferase (MHT) enzyme transfers the methyl group from the ubiquitous metabolite S-adenoyl methionine (SAM) to a halide ion. Using a synthetic metagenomic approach, we chemically synthesized all 89 putative MHT genes from plants, fungi, bacteria, and unidentified organisms present in the NCBI sequence database. The set was screened in Escherichia coli to identify the rates of CH3Cl, CH3Br, and CH3I production, with 56% of the library active on chloride, 85% on bromide, and 69% on iodide. Expression of the highest activity MHT and subsequent engineering in Saccharomyces cerevisiae results in productivity of 190 mg/L-h from glucose and sucrose. Using a symbiotic co-culture of the engineered yeast and the cellulolytic bacterium Actinotalea fermentans, we are able to achieve methyl halide production from unprocessed switchgrass (Panicum virgatum), corn stover, sugar cane bagasse, and poplar (Populus sp.). These results demonstrate the potential of producing methyl halides from non-food agricultural resources.