The effects of internal adaptation dynamics on the self-organized aggregation of chemotactic bacteria are investigated by Monte Carlo (MC) simulations based on a two-stream kinetic transport equation coupled with a reaction–diffusion equation of the chemoattractant that bacteria produce. A remarkable finding is a nonmonotonic behavior of the peak aggregation density with respect to the adaptation time; more specifically, aggregation is the most enhanced when the adaptation time is comparable to or moderately larger than the mean run time of bacteria. Another curious observation is the formation of a trapezoidal aggregation profile occurring at a very large adaptation time, where the biased motion of individual cells is rather hindered at the plateau regimes due to the boundedness of the tumbling frequency modulation. Asymptotic analysis of the kinetic transport system is also carried out, and a novel asymptotic equation is obtained at the large adaptation-time regime while the Keller–Segel type equations are obtained when the adaptation time is moderate. Numerical comparison of the asymptotic equations with MC results clarifies that trapezoidal aggregation is well described by the novel asymptotic equation, and the nonmonotonic behavior of the peak aggregation density is interpreted as the transient of the asymptotic solutions between different adaptation time regimes.

内部适应动力学对趋化细菌自组织聚集的影响通过蒙特卡罗 (MC) 模拟进行研究，该模拟基于双流动力学传输方程以及细菌产生的趋化剂的反应扩散方程。一个显着的发现是峰值聚集密度相对于适应时间的非单调行为；更具体地说，当适应时间与细菌的平均运行时间相当或稍大时，聚集的增强作用最大。另一个奇怪的观察结果是在非常大的适应时间内形成梯形聚集轮廓，由于翻滚频率调制的有界性，在高原状态下，单个细胞的偏置运动受到相当大的阻碍。还进行了动力学传输系统的渐近分析，在大适应时间范围内获得了新的渐近方程，而在适应时间适中时获得了 Keller-Segel 型方程。渐近方程与 MC 结果的数值比较表明梯形聚合很好地由新的渐近方程描述，峰值聚合密度的非单调行为被解释为不同适应时间制度之间渐近解的瞬态。