Collaborative Research: Identifying the basis of fitness against protozoan grazing in cyanobacteria: From quantitative genomics to molecular mechanisms

蓝藻是水生环境中重要的光合微生物，它们在食物网的基础上占据中心位置。此外，某些种类会产生毒素，并能够形成有害的藻华。由于富营养化和温度升高，预计未来这些水华的发生率将会增加。控制蓝藻种群的因素之一是捕食，但很少知道的生化和遗传机制之间的相互作用的蓝藻和他们的捕食者。研究人员将确定影响它们对捕食者易感性的蓝藻基因，以了解捕食机制。这些知识将有助于指导娱乐和饮用淡水资源的管理，以及用于生物技术应用的大规模户外蓝藻培养，这通常受到捕食者的阻碍。由于有毒藻华是公众普遍关心的问题，研究人员将把这个项目的各个方面纳入他们的教学和推广演讲中，以吸引学生和公众参与科学的过程及其对环境问题的应用。他们还将为代表性不足的高中生开发一个课程模块，向他们介绍水生环境中细菌的存在、数量和作用。该项目涉及的生理机制的蓝藻抵抗捕食的原生生物。具体来说，本项目的主要目的是确定在变形虫和纤毛虫捕食者的选择压力下，单细胞蓝藻长聚球菌适应性的基因和过程。研究人员已经开发了实验室模型系统来研究放牧相互作用，并将使用最先进的随机条形码转座子诱变（RB-TnSeq）和组学方法以及遗传、生化和生理方法来研究这些相互作用。他们对阿米巴原虫放牧的初步研究表明，细胞表面的几个组成部分在放牧条件下增加适应性的重要性。研究人员将在这些初步发现的基础上，确定S. elongatus o抗原突变体和其他被RB-TnSeq识别的基因破坏的突变体对阿米巴原虫捕食者的放牧抗性机制。他们将进行类似的分析，以确定在游动的纤毛虫食草动物存在的情况下影响蓝藻适应性的基因和过程。这些比较研究将为蓝藻逃避捕食者的策略提供重要的见解。研究人员还将把研究纳入高中学生的模块，并让本科生、研究生和博士后学者参与研究。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Cyanobacteria are important photosynthetic microorganisms in aquatic environments, where they occupy a central position at the base of the food web. In addition, certain species produce toxins and are capable of forming harmful algal blooms. Occurrences of these blooms are expected to increase in the future due to eutrophication and increasing temperatures. One of the factors controlling cyanobacterial populations is predation, but very little is known about the biochemical and genetic mechanisms governing the interactions between cyanobacteria and their predators. The researchers will identify cyanobacterial genes that affect their susceptibility to predators in order to understand predation mechanisms. This knowledge will be useful in guiding the management of recreational and drinking freshwater resources, and that of large scale outdoor culturing of cyanobacteria for biotechnological applications, which is often hampered by predators. Because toxic algal blooms are of general public interest, the researchers will incorporate aspects of this project into their teaching and outreach presentations to engage students and the public in the process of science and its application to environmental problems. They will also develop a module of classes for underrepresented high school students that will introduce them to the presence, abundance, and role of bacteria in aquatic environments. This project concerns physiological mechanisms underlying the resistance of cyanobacteria to predation by protists. Specifically, the main objective of this project is to identify genes and processes governing the fitness of the unicellular cyanobacterium Synechococcus elongatus under selective pressure by amoebal and ciliate predators. The investigators have developed laboratory model systems to study grazing interactions and will study these interactions with state-of-the-art random barcode transposon mutagenesis (RB-TnSeq) and omics approaches, as well as genetic, biochemical, and physiological methods. Their preliminary work on amoebal grazing has pointed to the importance of several components of the cell surface in increasing fitness under grazing conditions. The investigators will build upon these preliminary findings and identify the mechanism of grazing resistance to amoebal predators in S. elongatus O-antigen mutants and other mutants disrupted in genes identified by RB-TnSeq. They will perform similar analyses to identify genes and processes affecting cyanobacterial fitness in the presence of a swimming ciliate grazer. These comparative studies will provide major insight into cyanobacterial strategies for evasion of predators. The investigators will also incorporate the research into modules for high school students and involve undergraduates, graduates and postdoctoral scholars in the research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.