Researches on the diversity of growing patterns in biological systems

细菌根据营养物质浓度、基质硬度等环境条件的变化，形成具有特色和多样性的菌落。这意味着细菌通过集体或多细胞与环境相互作用来积极地生活，而不是单细胞被动地生活。为了阐明生物有机体的这种集体行为，我们从微观和宏观两方面研究了细菌菌落形成的生长机制和形态变化。我们建立了营养物浓度和基质柔软度变化时的形态图。我们还阐明了枯草芽孢杆菌和奇异变形杆菌各种菌落模式的生长条件和特点。从理论上讲，我们已经彻底研究了用反应-扩散方法如何很好地描述我们的实验观察。这些结果不仅有助于细菌菌落形成的研究，而且有助于扩大一般生物种群模式形成的实验和理论研究。奇异变形杆菌（Proteus mirabilis）通过重复的集体迁移和交替休息，形成宏观上几乎完美的同心圆状菌落，菌落间距近似相等。我们阐明了同心圆状菌落重复界面生长的现象学机制。

Bacteria form characteristic and diverse colonies according to variation of environmental conditions such as nutrient concentration and substrate hardness. This implies that bacteria live actively by interacting collectively or multicellularly with their environment, instead of living unicellularly and passively. In order to elucidate this kind of collective behavior of biological organisms we have studied the growth mechanism and morphological change in colony formation of bacteria both microscopically and macroscopically. We have established morphological diagrams when varying both nutrient concentration and substrate softness. We have also elucidated the growth conditions and characteristics of various colony patterns for species Bacillus subtilis and Proteus mirabilis. Theoretically we have thoroughly investigated how well we can describe our experimental observations from the reaction-diffusion approach. All these results contribute not only to the study of colony formation of bacteria but also to the enlargement of experimental and theoretical studies on pattern formation of the population of biological organisms in general. The species Proteus mirabilis forms macroscopically almost perfect concentric-ring like colonies with approximately equal spacing by repeating collective migration and rest alternately. We have elucidated phenomenological mechanism for the repeated interface growth of the concentric-ring like colonies.