Fungi and bacteria often share common microhabitats. Their co-occurrence and coevolution give rise to manifold ecological interactions in the mycosphere, here defined as the microhabitats surrounding and affected by hyphae and mycelia. The extensive structure of mycelia provides ideal “logistic networks” for transport of bacteria and matter in structurally and chemically heterogeneous soil ecosystems. We describe the characteristics of the mycosphere as a unique and highly dynamic bacterial habitat and a hot spot for contaminant biotransformation. In particular, we emphasize the role of the mycosphere for (i) bacterial dispersal and colonization of subsurface interfaces and new habitats, (ii) matter transport processes and contaminant bioaccessibility, and (iii) the functional stability of microbial ecosystems when exposed to environmental fluctuations such as stress or disturbances. Adopting concepts from ecological theory, the chapter disentangles bacterial–fungal impacts on contaminant biotransformation in a systemic approach that interlinks empirical data from microbial ecosystems with simulation data from computational models. This approach provides generic information on key factors, processes, and ecological principles that drive microbial contaminant biotransformation in soil. We highlight that the transport processes create favorable habitat conditions for efficient bacterial contaminant degradation in the mycosphere. In-depth observation, understanding, and prediction of the role of mycosphere transport processes will support the use of bacterial–fungal interactions in nature-based solutions for contaminant biotransformation in natural and man-made ecosystems, respectively.

真菌和细菌通常共享常见的微生境。它们的共同出现和共同进化在支原体层中引起了多种生态相互作用，此处被定义为围绕菌丝和菌丝体并受其影响的微生境。菌丝体的广泛结构为细菌和物质在结构和化学异质土壤生态系统中的运输提供了理想的“物流网络”。我们将分枝杆菌的特征描述为独特且高度动态的细菌栖息地和污染物生物转化的热点。特别是，我们强调了菌落在以下方面的作用：（i）细菌散布和定居在地下界面和新的生境中；（ii）物质的运输过程和污染物的生物可及性，（iii）当受到压力或干扰等环境波动的影响时，微生物生态系统的功能稳定性。本章采用生态学理论的概念，以一种系统的方法来分解细菌-真菌对污染物生物转化的影响，该方法将微生物生态系统的经验数据与计算模型的模拟数据相互关联。这种方法提供了驱动土壤中微生物污染物生物转化的关键因素，过程和生态原理的一般信息。我们着重指出，运输过程为真菌层中有效的细菌污染物降解创造了有利的栖息地条件。深入观察，理解，