SBIR Phase II: Xylose Isomerase from Marine Bacteria for Cellulosic Ethanol

这个小企业创新研究（SBIR）第二阶段项目将开发木糖异构酶（Xi）酶从海洋细菌作为一个过程的一部分，将生物质转化为乙醇。木糖异构酶将木糖（生物质中第二常见的糖）转化为木酮糖。木糖不能被酿酒酵母发酵成乙醇，但木酮糖可以。先前的Xi酶由于pH和抑制化合物的不相容性而不能与发酵一起工作。成功的第一阶段提案确定了这种海洋Xi能够进行木糖到乙醇的同时异构化和发酵（SIF）。木糖向乙醇的高效转化可以将总工艺产率提高20 - 40%。第二阶段项目将优化酶在天然和高生产力异源宿主中的生产，从而导致新酶的低成本来源。优化的酶将进一步表征，然后在200升生物反应器中生产，以证明可扩展性，从而实现商业化。该项目更广泛的影响/商业潜力是使纤维素乙醇的经济有效的商业化生产成为可能。 根据阿贡国家实验室的数据，来自当地纤维素生物质的乙醇是一种可持续的运输燃料，平均可减少87%的温室气体排放。的GREET模型。相对于石油基燃料，尾气排放的毒性也有所降低。作为一种国内燃料来源，纤维素乙醇增加了美国的能源安全，并加强了我们的经济。通过创造就业机会和将美元循环到美国经济中，纤维素乙醇改善了贸易逆差，减少了对外国石油的依赖。通过开发直接添加到发酵中的低成本酶，避免了转基因发酵生物的困难。 这不仅简化了乙醇生产过程，还减少了可能进入食物链的副产品中的转基因成分。

This Small Business Innovation Research (SBIR) Phase II project will develop the xylose isomerase (XI) enzyme from a marine bacterium as part of a process to convert biomass to ethanol. Xylose isomerase converts xylose, the second most common sugar in biomass, into xylulose. Xylose is not fermented to ethanol by brewing yeast, but xylulose is. Previous XI enzymes are unable to work in conjunction with fermentation due to incompatibilities in pH and inhibiting compounds. The successful Phase 1 proposal identified this marine XI as capable of performing Simultaneous Isomerization and Fermentation (SIF) of xylose to ethanol. High efficiency conversion of xylose to ethanol can improve overall process yield by 20-40%. The Phase II project will optimize the production of the enzyme in native and high-productivity heterologous hosts leading to a low cost source of the new enzyme. The optimized enzyme will be further characterized and then produced in a 200 liter bioreactor to demonstrate scalability leading to commercialization.The broader impact/commercial potential of this project is to enable the cost-effective commercial production of cellulosic ethanol. Ethanol from local cellulosic biomass is a sustainable transportation fuel that reduces greenhouse gas emissions by an average of 87% according to the Argonne National Lab?s GREET model. The toxicity of tailpipe emissions are also reduced relative to petroleum-based fuels. As a domestic source of fuel, cellulosic ethanol adds to U.S. energy security and strengthens our economy. By creating jobs and recycling dollars into the U.S. economy, cellulosic ethanol improves the trade deficit and lessens the dependence on foreign petroleum. By developing a low-cost enzyme that is added directly to the fermentation, difficulties with genetically modified fermentation organisms are avoided. This not only simplifies the ethanol production process, but also reduces the GMO content of co-products that may enter the food chain.