Telagathoti Anusha, Probst Maraike, Peintner Ursula
Institute of Microbiology, University of Innsbruck, Innsbruck, Austria.
Front Microbiol. 2021 Jul 1;12:669784. doi: 10.3389/fmicb.2021.669784. eCollection 2021.
Mortierellaceae species are among the most frequent and globally distributed soil fungi. However, the factors shaping their diversity and distribution remain obscure. Several species have been reported to be associated to bacteria, but the kind and frequency of such associations were not addressed up to now. We hypothesized that such associations could be important for Mortierellaceae ecology. Therefore, our aim was to understand the driving factors responsible for the Mortierellaceae diversity, community composition and bacterial associations in alpine and subalpine habitats. For answering our question, we collected both snow-free and snow-covered soil at sampling sites from different habitats: bare alpine soil in a glacier forefield, alpine dwarf-willow habitats, and high-altitude forests. The isolations were carried out by direct cultivation without any antibiotics to the isolation media. Altogether, we obtained 389 Mortierellaceae isolates representing 29 operational taxonomic units (OTUs). Many OTUs could be placed to the genera , , and , but others could not unambiguously be assigned to a genus. Our results demonstrate that both, the distribution as well as the diversity of the Mortierellaceae species, were significantly influenced by habitat, soil pH, and snow-cover. We noticed that >30% of our isolates were associated to a non-contaminant bacterium. The bacteria associated to our Mortierellaceae isolates belonged to seven different genera. was the most frequently detected genus associated to the isolated Mortierellaceae species and it was found to be species-specific. Mortierellaceae-bacteria pairs, including those with , were influenced by location, habitat, and snow-cover. The majority of the fungus-bacterium associations were potentially epihyphal, but we also detected potential endohyphal bacterial species belonging to , and . Taken together, the non-random associations we detected suggest that fungus-bacterium associations are ecologically meaningful - an interesting path that needs to be investigated further.
被孢霉科物种是最常见且全球分布的土壤真菌之一。然而，塑造其多样性和分布的因素仍不清楚。据报道，有几种物种与细菌有关，但到目前为止，此类关联的种类和频率尚未得到研究。我们推测这种关联可能对被孢霉科的生态学很重要。因此，我们的目的是了解导致高山和亚高山栖息地中被孢霉科多样性、群落组成和细菌关联的驱动因素。为了回答我们的问题，我们在不同栖息地的采样点收集了无雪和有雪覆盖的土壤：冰川前缘的裸露高山土壤、高山矮柳栖息地和高海拔森林。分离培养是通过直接培养进行的，分离培养基中不添加任何抗生素。我们总共获得了389株被孢霉科分离株，代表29个操作分类单元（OTU）。许多OTU可以归类到被孢霉属、小克银汉霉属和根霉属，但其他的无法明确归为某一属。我们的结果表明，被孢霉科物种的分布和多样性均受到栖息地、土壤pH值和积雪覆盖的显著影响。我们注意到，超过30%的分离株与一种非污染细菌有关。与我们的被孢霉科分离株相关的细菌属于七个不同的属。节杆菌属是与分离出的被孢霉科物种相关的最常检测到的属，并且发现它具有物种特异性。被孢霉科与细菌的配对，包括与节杆菌属的配对，受到位置、栖息地和积雪覆盖的影响。大多数真菌与细菌的关联可能是菌丝表面的，但我们也检测到了属于节杆菌属、微杆菌属和芽孢杆菌属的潜在菌丝内细菌物种。综上所述，我们检测到的非随机关联表明真菌与细菌的关联在生态上是有意义的——这是一条需要进一步研究的有趣途径。
