A biofilm is a self-contained community of bacteria that uses signaling molecules called autoinducers (AIs) to coordinate responses through the process of quorum sensing. Biofilms exhibit a dual role that drives interest in both combating antimicrobial resistance (AMR) and leveraging their potential in bioprocessing, since their products can have commercial potential. Previous work has demonstrated how the distinct anisotropic channel geometry in some biofilms affects AIs propagation therein. In this paper, a 2D anisotropic biofilm channel model is extended to be a time-varying channel (TVC), in order to represent the diffusion dynamics during the maturation phase when water channels develop. Since maturation is associated with the development of anisotropy, the time-varying model captures the shift from isotropic to anisotropic diffusion. Particle-based simulation results illustrate how the TVC is a hybrid scenario incorporating propagation features of both isotropic and anisotropic diffusion. This hybrid behavior aligns with biofilm maturation. Further study of the TVC includes characterization of the mutual information (MI), which reveals that an increased AI count, reduced transmitter -- receiver distance, greater degree of anisotropy, and shorter inter-symbol interference lengths increase the MI. Finally, a brief dimensional analysis demonstrates the scalability of the anisotropic channel results for larger biofilms and timescales.

翻译：生物膜是一种自组织的细菌群落，通过称为自诱导物（AIs）的信号分子，经由群体感应过程协调响应。生物膜具有双重作用，既因其在对抗抗菌素耐药性（AMR）中的重要性，又因其在生物加工中的潜在应用价值而备受关注，其产物可能具备商业潜力。先前的研究已揭示某些生物膜中独特的各向异性通道几何结构如何影响AIs在其中的传播。本文将一个二维各向异性生物膜通道模型扩展为时变通道（TVC）模型，以表征水通道形成过程中成熟阶段的扩散动力学。由于成熟阶段与各向异性的发展相关，时变模型捕捉了从各向同性扩散向各向异性扩散的转变。基于粒子的仿真结果表明，TVC是一种融合了各向同性与各向异性扩散传播特征的混合场景。这种混合行为与生物膜的成熟过程相符。对TVC的进一步研究包括对互信息（MI）的表征，结果表明：增加AI数量、减小发射器与接收器距离、提高各向异性程度以及缩短符号间干扰长度均可提升MI。最后，简要的量纲分析证明了各向异性通道结果在更大生物膜和更长时间尺度上的可扩展性。