Browsing by Subject "Capillary forces"
Now showing 1 - 1 of 1
- Results Per Page
- Sort Options
Item The hard life of swarming bacteria on soft substrates(2022-04-27) Gudavadze, Irakli; Florin, Ernst-Ludwig; Marder, Michael; Gordon, Vernita; Harshey, RasikaBacterial swarming is a rapid, collective movement of cells over a water-permeable surface, powered by rotating flagella. Spreading on a surface poses challenges not encountered during swimming in three-dimensional liquid. To cope with these challenges, bacteria undergo various morphological and physiological changes, including producing more flagella, cell elongation, and secreting surfactants. While hydration is essential for flagella-driven locomotion, it is poorly understood how bacteria draw and retain the necessary liquid around them, and how thick this liquid layer is. Here we use confocal laser scanning microscopy to experimentally determine the thickness of the liquid layer where bacteria swarm in a monolayer with the precision of a few tens of nm. In contrast to the current presumption in the field, we found this thickness to be smaller than a bacterium diameter, resulting in capillary forces on them. We developed a computer simulation to calculate these surface tension forces and found them to be on the order of a few nanonewtons, strongly confining bacteria to the surface. As a result, bacteria experience orders of magnitude greater resistive force during swarming than during swimming. We discuss how aforementioned morphological and physiological changes help swarming bacteria overcome con fining surface tension forces. These results pave the way for understanding how swarming bacteria spread on surfaces.