UNS: Collaborative Research: Biodiesel-derived butanol: Lipid vesicle mediated extraction enables continuous fermentation processes

PI：Geoffrey D. Bothun / Carmen Scholz提案编号：1508844 /1509244丁醇是一种很有前途的先进生物燃料，因为它具有接近汽油的高能量含量，可以作为替代燃料。 然而，丁醇相对于乙醇更难以通过发酵生产。 这是因为丁醇产物对发酵过程是有毒的，导致丁醇浓度低，成本太高而不能经济地回收。该项目将开发一种新的发酵工艺，该工艺使用无毒溶剂在生产丁醇时去除丁醇，从而降低毒性并提高丁醇的总产量。 此外，研究中选择的微生物巴氏梭菌（Clostridium pasteurianum）通过发酵生物柴油生产的副产品粗甘油来生产丁醇。通过这项调查，本科生和研究生将接受可再生燃料技术的培训，并将接受沟通技巧和公共宣传方面的专门培训。通过发酵生产丁醇通常会导致丁醇产量低，这是由于多种因素，包括微生物的丁醇耐受性低，难以将代谢途径重新定向到丁醇生物合成，和常规提取发酵技术的局限性。最近，正在进行的研究表明，细菌巴氏梭菌可以实现高丁醇产量使用粗甘油作为唯一的底物。粗甘油是由脂肪酸原料生产生物柴油的副产品。 本研究的总体目标是提高C.通过了解丁醇耐受性和生物相容性脂质囊泡在以粗甘油为底物的连续发酵过程中对其提取物的去除之间的关系， 将使用连续培养物来确定响应丁醇和底物添加的膜脂质组成和维持能量的变化。这种方法将用于连接耐受性，毒性和底物利用丁醇生产。 连续培养结合基于脂囊泡的萃取发酵具有通过两个过程提高丁醇产率的潜力。 首先，将研究囊泡介导的粗甘油提取以去除生物柴油衍生的甘油中的残留脂肪酸，已知该残留脂肪酸抑制甘油发酵成丁醇。 第二，原位提取发酵与生物相容性的脂质囊泡将研究其潜力，刺激代谢途径与丁醇生物合成通过质量作用效应。 该项目还提供机会，教育学生、教师和社区了解生物燃料的可持续生产，并通过罗得岛大学梅特卡夫学院培养学生在这方面的沟通技能。 将创建跨学科模块，来自罗得岛大学和亨茨维尔亚拉巴马大学的学生将共同研究与生物精炼厂操作相关的生物分离过程。

PI: Geoffrey D. Bothun / Carmen ScholzProposal Number: 1508844 / 1509244Butanol is a promising advanced biofuel because it has a high energy content approaching that of gasoline, and can serve as a drop-in replacement fuel. However, butanol is more difficult to produce by fermentation relative to ethanol. This is because the butanol product is toxic to the fermentation process, resulting in low concentrations of butanol that are too costly to recover economically. This project will develop a novel fermentation process that uses a nontoxic solvent to remove butanol while it is being produced, which reduces toxicity and increases overall butanol yield. Furthermore, the microorganism chosen for study, Clostridium pasteurianum, makes butanol from fermentation of crude glycerol, the by-product of biodiesel manufacture. Through this investigation, undergraduate and graduate students will be trained in renewable fuel technologies, and will receive specialized training in communication skills and public outreach.The production of butanol by fermentation typically results in low butanol yields due a variety of factors, including low butanol tolerance of microorganisms, difficulty in redirecting the metabolic pathway towards butanol biosynthesis, and limitations of conventional extractive fermentation techniques. Recently, ongoing research has shown that the bacterium Clostridium pasteurianum can achieve high butanol yields using crude glycerol as the sole substrate. Crude glycerol is the byproduct of biodiesel production from fatty acid feedstocks. The overall goal of this research is to enhance butanol production by C. pasteurianum through understanding of the relationships between butanol tolerance and its extractive removal by biocompatible lipid vesicles during continuous fermentation on crude glycerol as the substrate. Continuous cultures will be used to determine changes in membrane lipid composition and maintenance energy in response to butanol and substrate addition. This approach will used to connect tolerance, toxicity, and substrate utilization to butanol production. Continuous culture combined with lipid vesicle-based extractive fermentation has the potential to enhance the butanol yield through two processes. First, vesicle-mediated extraction of the crude glycerol will be studied to remove residual fatty acids in the biodiesel-derived glycerol, which are known to inhibit glycerol fermentation to butanol. Second, in situ extractive fermentation with the biocompatible lipid vesicles will be studied for its potential to stimulate the metabolic pathway associated with butanol biosynthesis through the mass-action effect. The project also provides opportunities to educate students, teachers, and communities about the sustainable production of biofuels, and to develop the communication skills of students in this context through Metcalf Institute at the University of Rhode Island. Interdisciplinary modules will be created where students from the University of Rhode Island and the University of Alabama in Huntsville will work together on bioseparation processes relevant to biorefinery operations.