Abstract

Fungal ecological interactions play a key role in structuring community assemblages. These associations may involve both antagonistic and synergistic relationships, which are commonly influenced by abiotic factors such as nutrient conditions. However, information for extreme, oligotrophic systems remain poor. Herein, interactions among key members of the aquatic transient fungal community (Aspergillus niger, Cladosporium sp., and Coprinellus micaceus) of a low-nutrient freshwater system in the Cuatro Ciénegas Basin, Mexico were studied. Pairwise interaction bioassays were explored in vitro under different nutrient conditions, including carbohydrates-rich, carbohydrates and amino peptides-rich, and low nutrients. Our results indicated that antagonistic patterns prevail among the studied taxa. However, nutrient-dependent changes were observed in Cladosporium sp. shifting to synergy under carbohydrates-rich conditions, suggesting changes in the fungal community composition as a result of nutrient enrichment. Remarkably, our findings contrast with previous work demonstrating mainly synergistic interactions between our tested fungal isolates and co-occurring autochthonous bacteria (Aeromonas spp. and Vibrio sp.) under low-nutrient conditions. This observation may indicate that bacteria and fungi exhibit distinct community-level responses, driven by nutrient conditions. This contributes to the knowledge of fungal community dynamics and interspecific interactions in an oligotrophic ecosystem, highlighting the relevance of nutrient-based shifts and antagonistic interactions in ecosystem dynamics.

摘要

真菌生态相互作用在构建社区集合体中起关键作用。这些关联可能涉及拮抗关系和协同关系，通常受非生物因素（如营养状况）的影响。但是，有关极端贫营养系统的信息仍然很少。在此，水生真菌瞬态社区主要成员（之间的相互作用黑曲霉，枝孢属，Coprinellus micaceus）在夸Ciénegas盆地低营养的淡水系统，墨西哥进行了研究。体外探索成对相互作用生物测定在不同的营养条件下，包括富含碳水化合物，富含碳水化合物和氨基肽的营养素和低营养素。我们的结果表明，在研究的类群中，对抗性模式占主导。但是，在Cladosporium sp。中观察到了养分依赖性变化。在富含碳水化合物的条件下转变为协同作用，这表明由于营养富集，真菌群落组成发生了变化。值得注意的是，我们的发现与以前的研究结果相反，之前的研究表明我们测试的真菌分离物与共生的土生细菌（气单胞菌和弧菌）之间主要是协同相互作用。在低营养条件下）。该观察结果可能表明，细菌和真菌在营养条件的驱动下表现出不同的群落水平响应。这有助于了解贫营养型生态系统中的真菌群落动态和种间相互作用，突出了基于营养物的变化和拮抗作用在生态系统动力学中的相关性。