Institute for Biological Physics and Center for Molecular Medicine Cologne, University of Cologne, Köln, Germany.
Institute for Biological Physics and Center for Molecular Medicine Cologne, University of Cologne, Köln, Germany.
Biophys J. 2021 Aug 17;120(16):3418-3428. doi: 10.1016/j.bpj.2021.06.022. Epub 2021 Jun 30.
Bacterial growth within colonies and biofilms is heterogeneous. Local reduction of growth rates has been associated with tolerance against various antibiotics. However, spatial gradients of growth rates are poorly characterized in three-dimensional bacterial colonies. Here, we report two spatially resolved methods for measuring growth rates in bacterial colonies. As bacteria grow and divide, they generate a velocity field that is directly related to the growth rates. We derive profiles of growth rates from the velocity field and show that they are consistent with the profiles obtained by single-cell-counting. Using these methods, we reveal that even small colonies initiated with a few thousand cells of the human pathogen Neisseria gonorrhoeae develop a steep gradient of growth rates within two generations. Furthermore, we show that stringent response decelerates growth inhibition at the colony center. Based on our results, we suggest that aggregation-related growth inhibition can protect gonococci from external stresses even at early biofilm stages.
细菌在菌落和生物膜内的生长是异质的。局部生长速率的降低与对各种抗生素的耐受性有关。然而，在三维细菌菌落中，生长速率的空间梯度还没有得到很好的描述。在这里，我们报告了两种用于测量细菌菌落中生长速率的空间分辨方法。随着细菌的生长和分裂，它们会产生一个与生长速率直接相关的速度场。我们从速度场中推导出生长速率的分布，并表明它们与单细胞计数得到的分布一致。使用这些方法，我们揭示了即使是由几千个人类病原体淋病奈瑟菌细胞起始的小菌落，在两代内也会在菌落中心形成一个陡峭的生长速率梯度。此外，我们还表明，严格响应会减缓菌落中心的生长抑制。基于我们的结果，我们提出，聚集相关的生长抑制可以保护淋病奈瑟菌免受外部压力，即使在早期生物膜阶段也是如此。
