Sustainable Bioconversion of Liquid Biofuels: Linking Organic Waste Processing and Microalgae Cultivation

藻类代表了一种潜在的有价值的可再生液体燃料，包括柴油和喷气燃料。这些液体燃料是从藻类生物量积累过程中产生的脂质中提取出来的，是飞机和机动车辆使用的石油基液体燃料的替代品。藻类生物量可以通过光合作用（光自养）、有机碳源（异养）或有机碳和阳光的结合（混合营养）来产生。不幸的是，仅从光合作用中产生的藻类生物燃料过程通常产生少量的藻类生物量和降低的脂质产量。另外，当补充有机碳和其他营养物质时，藻类可以产生更高水平的生物量并产生高脂质产量。然而，传统有机碳源（如葡萄糖）的加入增加了生产成本并阻碍了商业可行性。一个同样紧迫的可持续性问题是农业、工业和城市有机废物的积累和处置所造成的环境影响和成本。该研究项目将通过将有机废物处理过程与利用微藻生物处理生产液体燃料相结合，同时解决可持续性和能源问题。具体而言，该项目旨在改变废物处理方式，以产生更多的可被微藻消耗的有机碳源，并操纵微藻使这些宿主能够消耗来自人为有机废物的更多种类的碳源。该项目的具体目标如下：1)优化环境废物处理（发酵），以产生高产量的可被微藻消耗的有机营养物质；2)对微藻进行基因改造，使这些细胞能够消耗更多的有机废物副产品。在鲍尔实验室中，有机废物处理条件包括化学和生物预处理步骤以及碳和氮含量将被控制，以增加有机物转化为目标有机酸。不幸的是，虽然微藻可以消耗一些有机酸，但许多藻类无法处理废物处理过程中产生的其他有机酸副产品。因此，Betenbaugh实验室项目的第二个目标是重新编程微藻的细胞代谢，使它们能够消耗该物种通常不消耗的额外有机废物副产品。世界面临的三个最大的可持续发展挑战是环境污染、过度依赖不可再生的化石燃料和全球变暖。长期解决方案应考虑同时处理多个可持续性问题的整体方法。该项目通过将有机液体废物处理与微藻生长和脂质生产结合起来，以生产可再生液体生物燃料，解决了这些挑战。微藻利用有机废物将减少威胁我们河流、湖泊和海洋的农业、工业和家庭废物径流，并将在最需要就业机会的地区创造就业机会。这项技术可以与现有的农业和家庭废物处理设施相结合，促进可再生能源的产生、经济发展和社区自给自足。一个同样重要的目标是发展一种以可持续性为重点的新教育模式。通过与巴尔的摩少数族裔公立STEM高中的合作，学生们将在网络和实验室环境（包括当地的植物园）中学习如何用微藻生产生物燃料。此外，约翰霍普金斯大学正在开发以生物能源、生物可持续性和环境恢复为重点的课堂和实验室课程。因此，拟议中的项目将提供一个有价值的研究和教育平台，以培养下一代跨学科工程师和科学家，致力于寻找解决地球上紧迫的可持续发展问题的方法。

1236691Betenbaugh/BouwerAlgae represent a potentially valuable renewable source of liquid fuels including diesel and jet fuel. These liquid fuels are derived from the lipids generated during the accumulation of algal biomass and represent an alternative to petroleum-based liquid fuels for airplanes and motor vehicles. Algal biomass can be generated using photosynthesis (photoautotrophy), with organic carbon sources (heterotrophy), or using a combination of organic carbon and sunlight (mixotrophy). Unfortunately, algal biofuel processes derived from photosynthesis alone typically generate low amounts of algal biomass and reduced yields of the lipids. Alternatively, algae can generate much higher levels of biomass and produce high lipid yields when supplemented with organic carbon and other nutrients. However, the addition of traditional organic carbon sources such as glucose increases production costs and hinders commercial feasibility. An equally pressing sustainability problem is the environmental impacts and costs resulting from the accumulation and disposal of agricultural, industrial, and municipal organic wastes. This research program will simultaneously address both sustainability and energy issues by combining organic waste treatment processes with the generation of liquid fuels using microalgal bioprocessing. Specifically the project aims to alter waste treatment in order to generate increased amounts of organic carbon sources that can be consumed by microalgae and to manipulate microalgae to enable these hosts to consume a greater variety of carbon sources available from anthropogenic organic wastes. The specific objectives of the project are as follows: 1) Optimize environmental waste processing (fermentation) to generate high yields of organic nutrients that can be consumed by microalgae; 2) Manipulate microalgae genetically in order to allow these cells to consume a larger number of organic waste by-products. In the Bouwer laboratories, organic waste processing conditions including chemical and biological pretreatment steps as well as carbon and nitrogen content will be manipulated in order to increase organic matter conversion to target organic acids. Unfortunately, while microalgae can consume some organic acids, many algae are unable to process other organic acid by-products from waste treatment processes. Therefore, the second aim of the project in the Betenbaugh laboratory is to reprogram microalgae cellular metabolism to enable them to consume additional organic waste by-products that the species do not typically consume. Three of the greatest sustainability challenges facing the world are pollution of the environment, over-reliance on non-renewable fossil fuels, and global warming. Long-term solutions should consider holistic approaches that address multiple sustainability issues simultaneously. This program addresses these challenges by linking organic liquid waste disposal with microalgae growth and lipids production for the generation of renewable liquid biofuels. Utilization of organic wastes by microalgae will reduce agricultural, industrial and domestic waste runoff that threatens our rivers, lakes, and oceans and will lead to the creation of jobs in areas where the employment opportunities are most needed. This technology can integrate with existing agricultural and domestic waste-treatment facilities for renewable energy generation, economic development, and community self-sufficiency. An equally important goal will be the development of a new education paradigm focused on sustainability. Through a partnership with Baltimore's minority public STEM high schools, students will be educated using hands-on approaches to generate biofuels from microalgae in web-based and laboratory settings including a local arboretum. In addition, classroom and laboratory courses focused on bioenergy, biosustainability, and environmental recovery are under development at Johns Hopkins University. Thus, the proposed project will provide a valuable research and education platform to train the next generation of cross-disciplinary engineers and scientists dedicated to finding solutions to pressing sustainability issues on our planet.