Characterization of Fluorescence-Based Bacterial Biosensors that are Responsive to Water Stress

微生物的生长、生存和活动受到环境条件的强烈影响。虽然一个特定栖息地的平均环境条件很容易测量，但细菌在单个微栖息地中实际感知的条件对细菌的生态环境比平均条件更重要。目前，很少有环境监测工具能够在微生物的规模上发挥作用。这项研究的目标是开发一种新工具，使我们能够“从细菌的角度看待微栖息地”。这种被称为细菌生物传感器的工具是一种细菌，当它感知到特定的环境条件时，它会发生明显的变化。生物传感器是这项研究的重点，当细菌感觉到有限的水可用性时，它们会“发光”或发出荧光。本研究将描述几种设计用于植物叶片的水分胁迫响应细菌生物传感器的检测范围和特异性。本研究还将测试这些生物传感器的工作范围是否适合评估细菌暴露于植物叶片上有限水分的情况。植物叶片上的细菌暴露在环境条件的巨大而频繁的变化中，特别是在水分供应方面。了解这些细菌对水的限制程度，对于确定细菌在叶子上的生存策略，确定细菌在叶子上定居的过程，以及我们对这些生物的生态学的总体理解至关重要。这些信息将有助于制定策略，以最大限度地提高引入叶片的细菌的存活率，例如控制植物疾病或促进植物生长。此外，证明这些水分胁迫响应细菌生物传感器的有效性将为建立类似的工具来评估其他微生物栖息地以及叶片表面栖息地的其他环境条件奠定基础。

Microbial growth, survival and activity are strongly influenced by environmental conditions. Although the average environmental conditions across a given habitat can be easily measured, the conditions that are actually sensed by bacteria in individual microhabitats are more important to the ecology of the bacteria than the average conditions. Currently, there are few environmental monitoring tools that function on the scale of a microorganism. The goal of this study is to develop a new tool that will allow us to "see a microhabitat from a bacterium's perspective." This tool, called a bacteria] biosensor, is a bacterium that visibly changes when it senses a particular environmental condition. The biosensors that are the focus of this study are bacteria that "glow" or fluoresce when they sense limited water availability. This study will characterize the range of detection and specificity of several water stress-responsive bacterial biosensors that are designed for use on plant leaves. This study will also test whether the operating range of these biosensors is appropriate for evaluating bacterial exposure to limited water availability on plant leaves.Bacteria on plant leaves are exposed to large and frequent changes in environmental conditions, particularly in water availability. Understanding the extent to which these bacteria are limited for water is crucial to identifying the survival strategies bacteria employ on leaves, to identifying the process by which bacteria colonize leaves, and to our general understanding of the ecology of these organisms. This information will contribute to strategies for maximizing the survival of bacteria introduced onto leaves, such as for controlling plant diseases or promoting plant growth. Furthermore, demonstrating the effectiveness of these water-stress responsive bacterial biosensors will lay the foundation for building similar tools to evaluate other microbial habitats, as well as other environmental conditions in the leaf surface habitat.