Biological Utilization of Thermolytic Substrates by Bacteria and Microalgae: Addressing Toxicity of Substrate Contaminants

细菌和微藻对热解底物的生物利用：解决底物污染物的毒性

• 批准号: 1133319
• 负责人: Laura Jarboe
• 金额: $ 30万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1133319&HistoricalAwards=false
• 关键词: Biological; Utilization; Thermolytic; Substrates; Bacteria

PI: JarboeProposal Number: 1133319Intellectual MeritConverting biomass into biofuels through hybrid processes that integrate thermochemical and biochemical steps has the potential to reduce processing costs, but is understudied. This proposed research seeks to improve the capacity of microorganisms to produce biofuels using substrates derived from the fast pyrolysis of cellulosic biomass. The fast pyrolysis of biomass, which involves rapidly heating the material in the absence of oxygen and in presence of catalysts, yields a complex mixture called bio-oil. Fermentation of bio-oil is complicated by the fact that in addition to useful substrates, it also contains many inhibitory (contaminant) compounds, including furans and phenols. The overall goals of this proposed research are to increase the tolerance of two model microorganisms, Escherichia coli (ethanol) and Chlamydomonas reinhardtii (lipids for biodiesel), to the inhibitory contaminants found in bio-oil, and to improve the capacity of these organisms to ferment bio-oil fractions into biofuel. Metabolic evolution will be used to increase the robustness of these model microorganisms to the contaminants, largely because the bio-oil is complex and the mechanisms of inhibition are not known. The research plan has three objectives. The first objective is to use metabolic evolution to increase the tolerance of ethanol-producing E. coli to the inhibitory contaminants in the sugar-rich bio-oil fraction. The anhydrosugar levoglucosan is the most abundant substrate in the sugar-rich bio-oil fraction, but it is metabolized by most microorganisms. Therefore, an ethanol producing strain of E. coli will be engineered to utilize levoglucosan as a carbon and energy source. The second objective is use metabolic evolution to utilize the acetate-rich fraction of bio-oil by a heterotrophic, lipid-producing strain of C. reinhardti, and then increase the tolerance of C. reinhardtii to the inhibitory contaminants as well as acetate itself with the acetate-rich bio-oil fraction. The third objective is to reverse engineer the contaminant-tolerant E. coli strain developed under objective 1 through analysis of genome sequence and transcriptome data in order to identify the important mutations that enable contaminant tolerance.Broader ImpactsThe proposed education activities will train two graduate students from the disciplines of chemical engineering and food science, and engage three undergraduates to assist with the proposed research. Core concepts from the research topic will be introduced into three courses at Iowa State University (ISU): a sophomore-level Material and Energy Balances course, a graduate-level Metabolic Engineering, course, and a graduate-level course on the Thermochemical Processing of Biomass. With respect to K-12 outreach, the PI will develop a half-day module on bio-renewable chemicals for the ISU Science Bound program, a Saturday program that targets underrepresented middle school students. Students will have the opportunity to see an operating bioreactor and discuss how bio-renewable chemicals relate to their everyday life. Students will then play a web-based game that introduces the concept of metabolic evolution using the Biology in Motion Lab.

PI：Jarboe提案编号：1133319智力优点通过整合热化学和生化步骤的混合工艺将生物质转化为生物燃料具有降低加工成本的潜力，但尚未得到充分研究。 这项拟议的研究旨在提高微生物利用纤维素生物质快速热解产生的底物生产生物燃料的能力。 生物质的快速热解涉及在没有氧气和催化剂存在的情况下快速加热材料，产生一种称为生物油的复杂混合物。 生物油的发酵非常复杂，因为除了有用的底物外，它还含有许多抑制性（污染物）化合物，包括呋喃和酚类。 这项拟议研究的总体目标是提高两种模型微生物——大肠杆菌（乙醇）和莱茵衣藻（生物柴油的脂质）——对生物油中抑制性污染物的耐受性，并提高这些微生物的能力。将生物油馏分发酵成生物燃料。 代谢进化将用于提高这些模型微生物对污染物的鲁棒性，这主要是因为生物油很复杂并且抑制机制尚不清楚。 该研究计划有三个目标。 第一个目标是利用代谢进化来提高产乙醇大肠杆菌对富含糖的生物油馏分中的抑制性污染物的耐受性。 脱水糖左旋葡聚糖是富含糖的生物油馏分中最丰富的底物，但它被大多数微生物代谢。 因此，大肠杆菌的乙醇生产菌株将被改造为利用左旋葡聚糖作为碳和能源。 第二个目标是利用代谢进化，通过莱茵衣藻的异养、产脂菌株利用生物油中富含乙酸盐的部分，然后提高莱茵衣藻对抑制性污染物以及乙酸盐本身的耐受性。富含醋酸盐的生物油馏分。 第三个目标是通过分析基因组序列和转录组数据对目标 1 下开发的耐污染物大肠杆菌菌株进行逆向工程，以确定能够耐受污染物的重要突变。更广泛的影响拟议的教育活动将培训来自以下国家的两名研究生：化学工程和食品科学学科，并聘请三名本科生协助拟议的研究。 该研究主题的核心概念将被引入爱荷华州立大学 (ISU) 的三门课程：二年级材料和能量平衡课程、研究生水平代谢工程课程和研究生水平热化学加工课程。生物质。 在 K-12 外展方面，PI 将为 ISU Science Bound 项目开发一个为期半天的生物可再生化学品模块，该项目是一个针对代表性不足的中学生的周六项目。 学生将有机会参观正在运行的生物反应器，并讨论生物可再生化学品与他们的日常生活有何关系。 然后，学生将使用运动实验室中的生物学玩一个基于网络的游戏，介绍代谢进化的概念。