NSF/EPA TSE: Novel Compressed Solvent Extraction Processes for Enhanced Biomass Conversion by Thermophilic Bacteria

提出的工作的总体目标是证明使用压缩或超临界溶剂提取发酵挥发性产品的可行性。该项目将重点关注通过分解纤维的嗜热细菌热细胞梭菌从生物质发酵中高效地连续回收乙醇。这种生物能够直接从纤维生物质中产生相当数量的乙醇，但受到相对稀释的乙醇的抑制。主要研究人员（pi）的假设是，压缩溶剂能够有效地提取产物，从而减少产物抑制，从而提高发酵速率和产量。超临界流体萃取发酵具有类气体传质特性、溶剂强度可调性好、易于溶剂再生和减压回收等优点。具体目标是：(i)表征在可溶性和不可溶性碳水化合物存在下压缩溶剂对热梭菌生长和代谢的影响；（ii）演示使用压缩流体就地去除乙醇，并评估热梭菌的代谢活性与提取条件的关系；（iii）建立一个数学模型，以促进压缩提取发酵过程的设计和分析。该奖项由美国国家科学基金会颁发，作为美国国家科学基金会/美国环保署可持续环境技术联合计划的一部分。

The overall goal of the proposed work is to demonstrate the feasibility of extractive fermentation of volatile products using a compressed or supercritical solvent. The project will focus on the efficient continuous recovery of ethanol from biomass fermentation by the fibrolytic thermophilic bacteria, Clostridium thermocellum. This organism is capable of producing considerable amounts of ethanol directly from fibrous biomass, but is inhibited by the presence of relatively dilute ethanol. The Principal Invertigators' (PIs) hypthesis is that a compressed solvent is capable of efficiently extracting product so as to reduce product inhibition and thereby increase the fermentation rate and yield. Supercritical fluid extractive fermentation would have the advantages of gas-like mass transfer properties, solvent strength tunability, and ease of solvent regeneration and product recovery through depressurization. The specific objectives are to: (i) characterize effects of compressed solvents on the growth and metabolism of Clostridium thermocellum in the presence of soluble and insoluble carbohydrates; (ii) demonstrate in situ ethanol removal using a compressed fluid and evaluate the metabolic activity of Clostridium thermocellum as a function of extraction conditions; and (iii) develop a mathematicl model which will facilitate the design and analysis of compressed extractive fermentation processes. This award is made by NSF as part ofthe joint NSF/EPA Program on Technologies for a SustainableEnvironment.