Sokolov Andrey, Goldstein Raymond E, Feldchtein Felix I, Aranson Igor S
Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Sep;80(3 Pt 1):031903. doi: 10.1103/PhysRevE.80.031903. Epub 2009 Sep 10.
High-resolution optical coherence tomography is used to study the onset of a large-scale convective motion in free-standing thin films of adjustable thickness containing suspensions of swimming aerobic bacteria. Clear evidence is found that beyond a threshold film thickness there exists a transition from quasi-two-dimensional collective swimming to three-dimensional turbulent behavior. The latter state, qualitatively different from bioconvection in dilute bacterial suspensions, is characterized by enhanced diffusivities of oxygen and bacteria. These results emphasize the impact of self-organized bacterial locomotion on the onset of three-dimensional dynamics, and suggest key ingredients necessary to extend standard models of bioconvection to incorporate effects of large-scale collective motion.
高分辨率光学相干断层扫描技术被用于研究含有游动需氧细菌悬浮液的可调节厚度的独立薄膜中大规模对流运动的起始情况。有明确证据表明，超过临界薄膜厚度后，会存在从准二维集体游动到三维湍流行为的转变。后一种状态与稀细菌悬浮液中的生物对流在性质上不同，其特征是氧气和细菌的扩散率增强。这些结果强调了自组织细菌运动对三维动力学起始的影响，并提出了将生物对流标准模型扩展以纳入大规模集体运动效应所需的关键要素。
