The biofilm wrinkle evolution is the growth mechanism by which bacteria regulate their physiological state in response to the environmental change. We use the parameter of surface complexity to describe different wrinkle patterns. The surface complexity is defined that the biofilm surface area contact with the air is divided by the projected area of the biofilm. We find that the biofilm surface complexity variation is positively proportional to the number of spores. Although each wrinkle pattern has various wrinkle thickness and width, surface complexities of some patterns are almost same, which guarantees cells have enough living space. Through the observation of the growth of the damaged biofilm, we further find that the biofilm expansion along the circumferential direction is faster than that along radial direction, which means that the internal stress along the circumferential direction contributes the wrinkle formation. Our work provides a new perspective to study biofilm morphologies, and relates the morphology evolution with phenotypes in the Bacillus subtilis biofilm.

中文翻译：

---

枯草芽孢杆菌生物膜不断演变的皱纹模式为细胞提供更多的生存空间

生物膜皱纹演化是细菌响应环境变化调节其生理状态的生长机制。我们使用表面复杂度的参数来描述不同的皱纹模式。表面复杂度定义为与空气接触的生物膜表面积除以生物膜的投影面积。我们发现生物膜表面复杂性变化与孢子数量成正比。虽然每个皱纹图案的皱纹厚度和宽度各不相同，但有些图案的表面复杂程度几乎相同，这保证了细胞有足够的生存空间。通过观察受损生物膜的生长情况，我们进一步发现生物膜沿圆周方向的扩张速度比沿径向方向的扩张速度快，这意味着沿圆周方向的内应力有助于皱纹的形成。我们的工作为研究生物膜形态提供了新的视角，并将形态进化与枯草芽孢杆菌生物膜中的表型联系起来。