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

拟议工作的总体目标是证明使用压缩或超临界溶剂对挥发性产品进行萃取发酵的可行性。该项目将专注于从生物质发酵中高效、连续地回收乙醇，这些乙醇是由纤维溶解的嗜热菌--热梭菌--连续回收的。这种生物能够直接从纤维状生物质中产生相当数量的乙醇，但在相对稀薄的乙醇存在下受到抑制。主要逆转剂(PI)的假设是压缩的溶剂能够有效地提取产物，从而减少产物的抑制，从而提高发酵速度和产量。超临界流体萃取发酵具有类似气体的传质特性、溶剂强度可调、易于溶剂再生和减压回收产品等优点。其具体目标是：(I)表征压缩溶剂在存在可溶性和不溶性碳水化合物的情况下对热梭菌生长和代谢的影响；(Ii)展示利用压缩流体原位脱除乙醇并评估作为提取条件的热梭菌的代谢活性；以及(Iii)建立便于设计和分析压缩萃取发酵过程的数学模型。该奖项由NSF颁发，是NSF/EPA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.