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：2018
卷号：115
期号：51
页码：12979-12984
DOI：10.1073/pnas.1809374115
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Bacteria under external stress can reveal unexpected emergent phenotypes. We show that the intensely studied bacterium Escherichia coli can transform into long, highly motile helical filaments poized at a torsional buckling criticality when exposed to minimum inhibitory concentrations of several antibiotics. While the highly motile helices are physically either right- or left-handed, the motile helices always rotate with a right-handed angular velocity ω → , which points in the same direction as the translational velocity v → T of the helix. Furthermore, these helical cells do not swim by a “run and tumble” but rather synchronously flip their spin ω → and thus translational velocity—backing up rather than tumbling. By increasing the translational persistence length, these dynamics give rise to an effective diffusion coefficient up to 20 times that of a normal E. coli cell. Finally, we propose an evolutionary mechanism for this phenotype’s emergence whereby the increased effective diffusivity provides a fitness advantage in allowing filamentous cells to more readily escape regions of high external stress.
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