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

这个小企业创新研究（SBIR）二期项目将从一种海洋细菌中开发木糖异构酶（XI），作为将生物质转化为乙醇过程的一部分。木糖异构酶将生物质中第二常见的糖木糖转化为木糖。木糖不能被酿酒酵母发酵成乙醇，但木糖可以。由于pH和抑制化合物不相容，以前的XI酶无法与发酵一起工作。成功的第1阶段提案确定了这种海洋XI能够进行木糖同步异构化和发酵（SIF）到乙醇。木糖高效转化为乙醇可使整个工艺收率提高20-40%。二期项目将优化酶在原生和高产的异种宿主中的生产，从而获得低成本的新酶来源。优化后的酶将进一步表征，然后在一个200升的生物反应器中生产，以证明可扩展性，从而实现商业化。该项目的更广泛影响/商业潜力是使纤维素乙醇具有成本效益的商业生产成为可能。根据阿贡国家实验室（Argonne National Lab）的数据，从当地纤维素生物质中提取的乙醇是一种可持续的交通燃料，可以平均减少87%的温室气体排放。it’s GREET模型。与以石油为基础的燃料相比，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使美元循环进入美国经济，纤维素乙醇改善了贸易逆差，减少了对外国石油的依赖。通过开发一种低成本的酶，直接添加到发酵中，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，而且还减少了可能进入食物链的副产品的转基因含量。

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.