北京大學定量生物學中心

學術報告 

題    目: Causes and consequences of heterogeneous behavior in clonal bacterial populations

報告人:  Rolf Kümmerli

Associate Professor, University of Zurich, Switzerland

時    間: 10月23日（周一）13:00-14:00

地    點: 呂志和樓B101

主持人: 李志遠 研究員

摘 要:

Clonal cells often vary in their phenotype. Cellular heterogeneity can arise due to stochastic noise associated with intra-cellular processes. However, cellular heterogeneity can also have adaptive functions whereby it is beneficial for cells to express different phenotypes. Here, I present results from experiments with the bacterium Pseudomonas aeruginosa exploring the causes and consequences of cellular heterogeneity in the expression of cooperative traits. First, we focus on iron-scavenging siderophores shared between cells. We observe high variation in the expression of siderophore genes across cells, whereby heterogeneity is temporally stratified, influenced by the position of a cell within a colony, and inherited from mother to daughter cell. Our results suggest that cellular heterogeneity is the result of cells adjusting their behavior to fine-scale differences in their micro-environment and epigenetic inheritance. Second, we explore cellular heterogeneity in quorum-sensing communication. Here, we observe bimodal cellular responses, whereby a fraction of cells commits to quorum-sensing communication early one, while other cells delay their communication activities. Our results are compatible with a bet-hedging scenario, where clonal cells diverge in two distinct phenotypes to optimize performance at the group level. In sum, our findings help to obtain an integrative understanding of cellular heterogeneity in bacterial populations.

報告人簡介：

Rolf Kümmerli obtained his PhD from the University of Lausanne, Switzerland in 2006. Subsequently, he worked as a post-doctoral fellow at the University of Edinburgh, UK. In 2009, he became a junior research group leader at ETH Zurich. After moving to the University of Zurich in 2012 as an assistant professor, he was promoted to associate professor in 2018, where he is now chair for the evolution of human microbiomes and pathogens. His research interests are at the interface between microbiology, ecology and evolution, with a strong focus on microbe-microbe interactions and their consequences for community dynamics and host-pathogen interactions.