National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
Indian Institute of Science Education and Research, Mohali, India.
Nat Commun. 2024 Nov 8;15(1):9561. doi: 10.1038/s41467-024-53989-6.
Evidence from homogeneous liquid or flat-plate cultures indicates that biochemical cues are the primary modes of bacterial interaction with their microenvironment. However, these systems fail to capture the effect of physical confinement on bacteria in their natural habitats. Bacterial niches like the pores of soil, mucus, and infected tissues are disordered microenvironments with material properties defined by their internal pore sizes and shear moduli. Here, we use three-dimensional matrices that match the viscoelastic properties of gut mucus to test how altering the physical properties of their microenvironment influences the growth of bacteria under confinement. We find that low aspect ratio (spherical) bacteria form compact, spherical colonies under confinement while high aspect ratio (rod-shaped) bacteria push their progenies further outwards to create elongated colonies with a higher surface area, enabling increased access to nutrients. As a result, the population growth of high aspect ratio bacteria is, under the tested conditions, more robust to increased physical confinement compared to that of low aspect ratio bacteria. Thus, our experimental evidence supports that environmental physical constraints can play a selective role in bacterial growth based on cell shape.
均质液体或平板培养的证据表明，生化线索是细菌与其微环境相互作用的主要模式。然而，这些系统未能捕捉到物理约束对细菌在其自然栖息地的影响。细菌生境，如土壤、粘液和感染组织的孔隙，是具有由内部孔径和剪切模量定义的材料特性的无序微环境。在这里，我们使用与肠道粘液的粘弹性特性相匹配的三维基质来测试改变其微环境的物理特性如何影响细菌在受限环境下的生长。我们发现，低纵横比（球形）细菌在受限环境下形成紧密的球形菌落，而高纵横比（棒状）细菌将其后代向外推，形成具有更大表面积的伸长菌落，从而增加了对营养物质的获取。因此，在测试条件下，与低纵横比细菌相比，高纵横比细菌的种群增长对增加的物理限制更具鲁棒性。因此，我们的实验证据支持环境物理约束可以根据细胞形状在细菌生长中发挥选择性作用。
