Phenotypic heterogeneity and bet hedging in chemotaxis of Escherichia coli

大肠埃希菌趋化性是分析最多的简单行为反应模型系统之一。趋化性使细菌能够跟随营养和环境刺激的梯度，找到最适合生长的条件。它还在细菌的合作行为和毒力方面发挥着重要作用。实验和理论研究确立了大肠杆菌趋化性是进化优化细胞网络的一个例子，并对信号放大和稳健性等一般网络属性产生了许多见解。该项目的目标是研究趋化性的一个鲜为人知的方面，即趋化性基因在整个种群、大肠杆菌和其他模式细菌中表达的协同变异的起源和后果。我们进一步建议研究大肠杆菌种群依赖于环境选择来调节其异质性的能力。最后，我们的目标是通过建立一个协作性和异质性可调的人工协同系统来分析这种种群异质性和大肠杆菌趋化中的协同行为之间的相互作用。我们期望这个项目能显著提高我们对微生物行为中异质性和协同性的起源和后果的定量理解。

Escherichia coli chemotaxis is one of the most analyzed model systems of simple behavioural re-sponse. Chemotaxis allows bacteria to follow gradients of nutrients and environmental stimuli to find conditions that are optimal for growth. It further plays an important role in cooperative behaviour of bacteria and in virulence. Experimental and theoretical studies established E. coli chemotaxis as an example of an evolutionary optimized cellular network and yielded many insights into such general network properties as signal amplification and robustness. The goal of this project is to investigate one of the little studied aspects of chemotaxis, namely the origins and consequences of concerted variation in expression of chemotaxis genes across the population, in E. coli and in other model bacteria. We further propose to investigate the ability of E. coli population to adjust its heterogeneity dependent on the environmental selection. Finally, we aim to analyze the interplay between such population heterogeneity and cooperative behaviour in E. coli chemotaxis, also by establishing an artificial cooperating system with tuneable cooperativity and heterogeneity. We expect this project to significantly advance our quantitative understanding of the origins and consequences of heterogeneity and cooperativity in microbial behaviour.