STTR Phase I: Consolidated biosynthesis of methyl ethyl ketone from cellulosic biomass

这个小型企业技术转移(STTR)第一阶段项目计划开发一种新的低成本平台，使用一种新型的重组纤维素分解枯草芽孢杆菌菌株，直接从经过预处理的纤维素生物质中一步生产甲乙酮。甲乙酮(MEK)，又称2-丁酮，是仅次于丙酮的第二大商品酮。目前MEK只由2-丁醇氧化产生。然而，这种工业合成过程使用的原料来自石化产品，通常价格昂贵，而且不环保。迫切需要开发一种新的低成本和环境友好的方法来生产MEK，而不是通过2-丁醇来生产。纤维素生物质是最丰富的天然可再生资源，具有生产短期和长期可持续发展的宝贵生物商品的巨大潜力。然而，将非食用木质纤维原料转化为MEK的方法在经济上尚不可行，这是因为涉及纤维素酶的纤维素酶的成本很高，而且使用了挑剔的培养基。该项目将利用合成途径和代谢工程，将利用非纤维素的枯草芽孢杆菌转化为一种高效的纤维素利用菌，生产出产量高、效价高、适合工业发酵的MEK。如果该项目成功，将成为一个以非食品生物质为原料，采用强化生物加工工艺生产MEK的低成本平台。然后，MEK可用作油漆的溶剂，并用作生产其他化学品的中间体。因此，MEK可以很容易地在涂料行业和塑料制造业找到市场。更重要的是，MEK可以通过随后的加氢转化为辛烷异构体，可用于生产高级航空燃料。目前，MEK是通过温室气体排放的方法从石油衍生的化学品中合成的。到目前为止，由于工艺经济性较低，生产生物基MEK的努力很少。与开发其他微生物相比，建议的重组纤维素分解枯草杆菌将具有优势。此外，新的绿色技术将满足运营成本考虑、环境问题以及健康和安全法规。与传统机制相比，这条新的路线将更具成本效益和环境友好。如果在二期项目完成后成功商业化，这种基于生物的MEK生产技术将比传统方法具有显著的竞争优势，因为它更具商业吸引力，并支持社会的可持续发展。

This Small Business Technology Transfer (STTR) Phase I project proposes to develop a new low-cost platform for the production of methyl ethyl ketone directly from pretreated cellulosic biomass in a single step using a novel recombinant cellulolytic Bacillus subtilis strain. Methyl ethyl ketone (MEK), also referred to as 2-butanone, is the second most important commercial ketone after acetone. MEK is currently only produced by the oxidation of 2-butanol. However, this industrial synthesis process uses starting materials derived from petrochemicals and is generally expensive as well as not environmentally friendly. There is an urgent need to develop a novel cost-effective and environmentally friendly method to produce MEK other than through 2-butanol. The cellulosic biomass is the most abundant natural renewable resource and has great potential for the production of valuable biocommodities for both short- and long-term sustainability. However, the process for converting non-food lignocellulosic material into MEK is not yet economically feasible due to the high cost of the cellulase involved in cellulose hydrolysis and the use of fastidious culture media. Using synthetic pathway and metabolic engineering, this project will convert noncellulose-utilizing B. subtilis into an efficient cellulose utilizer to produce MEK with high yield and titer, suitable for industrial fermentation.The broader impact/commercial potential of this project, if successful, will be a low-cost platform for producing MEK from nonfood biomass in a process called consolidated bioprocessing. MEK may then be used as a solvent for paint, and serve as an intermediate in the production of other chemicals. Therefore, MEK could easily find a market in the paint industry and in plastics manufacturing. More importantly, MEK could be converted by subsequent hydrogenation into octane isomers that can be used to produce high-grade aviation fuel. Currently, MEK is synthesized from petroleum-derived chemicals via a method involving greenhouse gas emissions. So far, few efforts have been made to produce bio-based MEK due to low process economics. The proposed recombinant cellulolytic B. subtilis would have advantages over developing other microorganisms. In addition, the novel green technology will satisfy operational cost considerations, environmental concerns, and health and safety regulations. Compared to traditional mechanism, this novel route will be more cost-effective and environmentally friendly. If successfully commercialized after the completion of the Phase II project, this bio-based MEK production technology will have a significant competitive advantage over traditional methods because it is more commercially attractive and supports sustainable societal development.