NPIF: Photobioreactors for sustainable production of plant-driven biocompounds

从纸张，织物到木制品，植物产生了我们环境中使用的大部分天然材料[1]。植物还提供药物、染料、香料和其他专用化学品。虽然生物技术已经发展成为微生物和哺乳动物系统的工业规模细胞培养，但植物细胞几乎没有使用;有趣的是，植物驱动的产品通过植物途径的转基因引入在其他生物体中产生[2]。为什么植物细胞在工业生物技术中被忽视？据该领域主要公司的代表称，问题在于工业化植物细胞生物技术的工具和方案还不成熟，例如合适的生物反应器平台和高效细胞工厂的可用性。在为微生物和哺乳动物细胞开发的典型生物反应器中，植物细胞往往很脆弱;它们对培养基机械混合引起的剪切应力很敏感。此外，尽管植物细胞是自养的，但它们需要在缺乏光线的传统生物反应器内供应大量糖。具有讽刺意味的是，糖含量增加了微生物污染和感染的风险。因此，应开发允许光合作用的生物反应器（即光生物反应器）用于植物细胞培养。生物技术公司Xanthella已经建立了多功能的光生物反应器，用于培养各种藻类[3]。他们的系统通过管道供应空气，因此不涉及介质的机械混合，并且它们具有广泛的规模。在植物细胞工厂的选择方面，也存在着工具不完善的问题。爱丁堡大学中山研究组正在开发合成生物学工具箱，用于构建生产特定类型生物化合物的植物细胞工厂。本博士项目旨在为植物细胞培养和基于植物细胞的工业生物技术建立一个强大、低成本、可扩展的平台。将新的拟南芥细胞工厂系与Xanthella的光生物反应器相结合，我们将为基于植物细胞的工业生物技术开发两项创新：合适的生物反应器和精密控制细胞活动的工具箱。

From papers, fabrics to wood products, plants generate most of the natural materials used in our environment [1]. Plants also supply medicines, dyes, spices, and other specialized chemicals. While biotechnology has blossomed into industrial scale cell culturing for microbial and mammalian systems, plant cells are scarcely used; interestingly, plant-driven products are generated in other organisms via transgenic introduction of plant pathways [2]. Why are plant cells overlooked in industrial biotechnology? According to representatives of major companies in the field, the problem is simply that the tools and protocols are underdeveloped for industrial plant cell biotechnology, such as the suitable bioreactor platforms and the availability of high efficiency cell factories.Plant cells tend toward frail in typical bioreactors developed for microbes and mammalian cells; they are sensitive to the shear stress caused by mechanical mixing of the medium. Furthermore, even though plant cells are autotrophic, they need supply of a high amount of sugar inside traditional bioreactors devoid of light. Ironically, the sugar content increases the risk of microbial contamination and infection. Therefore, bioreactors that allow photosynthesis (i.e. photobioreactors) should be developed for plant cell culturing. The biotechnology company Xanthella has established versatile photobioreactors for culturing diverse algae species [3]. Their systems supply air via tubes and thus do not involve mechanical mixing of the medium, and they come in a wide range of scales. Underdeveloped tools also extend to the selection of plant cell factories; the Nakayama Group at the University of Edinburgh is developing a synthetic biology toolbox to create plant cell factories with enhanced capabilities to produce specific types of biocompounds.This PhD project aims to establish a robust, low-cost, and scalable platform for plant cell culturing and thus plant cell-based industrial biotechnology. Combining the novel Arabidopsis cell factory lines with Xanthella's photobioreactors, we will develop two enabling innovations for plant cell-based industrial biotechnology: the suitable bioreactors and sophisticated toolbox for precision control of the cell activities.