Identification of photoheterotrophic microorganisms in temperate freshwater lakes

光合作用以太阳能为燃料，由微小的藻类或浮游植物执行，是水生生态系统生产力的主要来源。然而，最近的研究表明，以前未知的利用太阳能的能力的微生物，即所谓的光异养生物，在海洋中大量存在，在淡水生态系统中也存在。与完全依赖基于叶绿素的光合作用生长的藻类不同，光异养生物使用称为视紫红质和细菌叶绿素的色素将太阳能转化为它们主要摄取的有机物质的食物补充剂。这个项目的目的是发现、描述和记录在温带淡水湖中组成这一不寻常的浮游植物群体的优势生物。由于它们的捕光能力和对基因工程的适应性，光异养生物可能会在未来的生物能源生产系统中发挥作用。研究结果将为淡水浮游植物生物勘探提供基线信息，以寻找潜在有用的微生物。这项工作的更广泛影响还包括尖端研究技术的进一步发展，例如研究单个细胞的完整基因组，用于可视化浮游植物的红外荧光显微镜，以及用于分离和研究浮游植物细胞的荧光激活细胞分选。一名博士后助理和最多三名本科生将在项目过程中接受培训，特别是在招收美洲原住民学生方面。将通过面向科学界的讲习班和高级课程以及面向公众的各种外展活动来广泛传播研究成果。

Fuelled by solar energy and performed by microscopic algae, or phytoplankton, photosynthesis is the primary source of productivity in aquatic ecosystems. However, recent studies suggest that microorganisms with previously unknown capabilities for harnessing solar energy, the so-called photoheterotrophs, are abundant in the oceans and are present in freshwater ecosystems as well. In contrast to algae, which completely depend on chlorophyll-based photosynthesis for their growth, photoheterotrophs use pigments called rhodopsins and bacteriochlorophylls to convert solar energy into a food supplement to their predominant diet of ingested organic matter. The aim of this project is to discover, describe, and document the predominant organisms that make up this unusual group of phytoplankton in temperate freshwater lakes. Due to their light-harvesting capacity and amenability to genetic engineering, photoheterotrophs may be useful in future bioenergy production systems. Research results will provide baseline information for freshwater phytoplankton bioprospecting, in a search for potentially useful microorganisms. The broader impacts of this work also include further development of cutting-edge research technologies, such as the study of a complete genome of a single cell, infrared epifluorescence microscopy for visualizing phytoplankton, and fluorescence-activated cell sorting to isolate and study phytoplankton cells for experiments. One postdoctoral associate and up to three undergraduate students will be trained during the course of the project, with particular effort placed on recruiting Native American students. Wide dissemination of research results will be achieved by workshops and advanced courses to the scientific community, as well as through diverse outreach activities to the general public.