Filamentous fungi play a key role as decomposers in Earth's nutrient cycles. In soils, substrates are heterogeneously distributed in microenvironments. Hence, individual hyphae of a mycelium may experience very different environmental conditions simultaneously. In the current work, we investigated how fungi cope with local environmental variations at single-cell level. We developed a method based on infrared spectroscopy that allows the direct, in-situ chemical imaging of the decomposition activity of individual hyphal tips. Colonies of the ectomycorrhizal Basidiomycete Paxillus involutus were grown on liquid media, while parts of colonies were allowed to colonize lignin patches. Oxidative decomposition of lignin by individual hyphae growing under different conditions was followed for a period of seven days. We identified two sub-populations of hyphal tips: one with low decomposition activity and one with much higher activity. Active cells secreted more extracellular polymeric substances and oxidized lignin more strongly. The ratio of active to inactive hyphae strongly depended on the environmental conditions in lignin patches, but was further mediated by the decomposition activity of entire mycelia. Phenotypic heterogeneity occurring between genetically identical hyphal tips may be an important strategy for filamentous fungi to cope with heterogeneous and constantly changing soil environments.

中文翻译：

---

在单细胞水平上调节真菌分解。

丝状真菌在地球养分循环中起分解剂的作用。在土壤中，基质在微环境中分布不均。因此，菌丝体的单个菌丝可能同时经历非常不同的环境条件。在当前的工作中，我们研究了真菌如何在单细胞水平上应对局部环境变化。我们开发了一种基于红外光谱的方法，该方法允许直接，原位化学成像单个菌丝尖端的分解活性。在液体培养基上生长外生菌根枯萎病杆菌（Paxillus involutus）的菌落，同时允许部分菌落定殖木质素斑块。木质素被在不同条件下生长的单个菌丝氧化分解的过程进行了7天。我们确定了菌丝尖端的两个亚群：一个具有低分解活性，另一个具有高得多的活性。活性细胞分泌更多的细胞外聚合物，并更强烈地氧化木质素。活性菌丝与非活性菌丝的比例在很大程度上取决于木质素斑块中的环境条件，但进一步受整个菌丝体分解活性的影响。在遗传上相同的菌丝尖端之间出现表型异质性可能是丝状真菌应对异质性和不断变化的土壤环境的重要策略。活性菌丝与非活性菌丝的比例在很大程度上取决于木质素斑块中的环境条件，但进一步受整个菌丝体分解活性的影响。在遗传上相同的菌丝尖端之间出现表型异质性可能是丝状真菌应对异质性和不断变化的土壤环境的重要策略。活性菌丝与非活性菌丝的比例在很大程度上取决于木质素斑块中的环境条件，但进一步受整个菌丝体分解活性的影响。在遗传上相同的菌丝尖端之间出现表型异质性可能是丝状真菌应对异质性和不断变化的土壤环境的重要策略。