Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Kgs Lyngby, Denmark.
Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena, Germany.
Nat Commun. 2024 May 27;15(1):4486. doi: 10.1038/s41467-024-48812-1.
Bacterial-fungal interactions influence microbial community performance of most ecosystems and elicit specific microbial behaviours, including stimulating specialised metabolite production. Here, we use a co-culture experimental evolution approach to investigate bacterial adaptation to the presence of a fungus, using a simple model of bacterial-fungal interactions encompassing the bacterium Bacillus subtilis and the fungus Aspergillus niger. We find in one evolving population that B. subtilis was selected for enhanced production of the lipopeptide surfactin and accelerated surface spreading ability, leading to inhibition of fungal expansion and acidification of the environment. These phenotypes were explained by specific mutations in the DegS-DegU two-component system. In the presence of surfactin, fungal hyphae exhibited bulging cells with delocalised secretory vesicles possibly provoking an RlmA-dependent cell wall stress. Thus, our results indicate that the presence of the fungus selects for increased surfactin production, which inhibits fungal growth and facilitates the competitive success of the bacterium.
细菌-真菌相互作用影响大多数生态系统的微生物群落性能，并引发特定的微生物行为，包括刺激专门的代谢产物的产生。在这里，我们使用共培养实验进化方法来研究细菌对真菌存在的适应，使用一个简单的细菌-真菌相互作用模型，包括细菌枯草芽孢杆菌和真菌黑曲霉。我们在一个进化种群中发现，枯草芽孢杆菌被选择用于增强脂肽表面活性剂的产生和加速表面扩散能力，从而抑制真菌的扩张和环境的酸化。这些表型可以通过 DegS-DegU 双组分系统中的特定突变来解释。在表面活性剂存在的情况下，真菌菌丝体表现出膨胀的细胞，其中分泌囊泡定位不当，可能引发 RlmA 依赖性细胞壁应激。因此，我们的结果表明，真菌的存在选择了增加表面活性剂的产生，从而抑制真菌的生长并促进细菌的竞争成功。
