期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：48
DOI：10.1073/pnas.2105138118
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Motility is one of the most striking bacterial behaviors common among many species. Motile bacteria can expand rapidly into previously unoccupied habitats, thus increasing fitness. Fast expansion is fostered by the sensing of gradients which the bacteria generate themselves and is further boosted by cell growth. Here we analyze the integrated dynamics of these processes mathematically. The relations obtained provide an analytical description of the expansion process and its dependence on core bacterial and environmental characteristics, like the growth rate, the abundance of chemical attractants in the surroundings, and the detection limit of the attractants.
Bacterial cells navigate their environment by directing their movement along chemical gradients. This process, known as chemotaxis, can promote the rapid expansion of bacterial populations into previously unoccupied territories. However, despite numerous experimental and theoretical studies on this classical topic, chemotaxis-driven population expansion is not understood in quantitative terms. Building on recent experimental progress, we here present a detailed analytical study that provides a quantitative understanding of how chemotaxis and cell growth lead to rapid and stable expansion of bacterial populations. We provide analytical relations that accurately describe the dependence of the expansion speed and density profile of the expanding population on important molecular, cellular, and environmental parameters. In particular, expansion speeds can be boosted by orders of magnitude when the environmental availability of chemicals relative to the cellular limits of chemical sensing is high. Analytical understanding of such complex spatiotemporal dynamic processes is rare. Our analytical results and the methods employed to attain them provide a mathematical framework for investigations of the roles of taxis in diverse ecological contexts across broad parameter regimes.
关键词：bacterial chemotaxis; range expansion; Keller–Segel model; Fisher wave; front propagation
