Assessment of Fungal spores and spore-like diversity in Environmental Samples by Targeted Lysis

Abstract

Abstract Resistant cells, such as spores are a vital part of the life cycle of fungi with essential roles in ecology and reproduction. These structures help fungi not only to disperse to other environments but also to survive long periods of time awaiting favorable growth conditions. As a result, fungal spores and resistant cells are part of the microbial seed bank, which is known to influence the microbial community composition, and contribute to the maintenance of diversity. Despite the importance of resistant cells in the life-cycles of fungi, and more largely, of microbial seed banks in the environment, the methods to study the diversity of fungal resistant cells only target spores dispersing in the air, omitting the diversity of these cells elsewhere. In this study, we applied a separation method based on lysis-resistance to enrich fungal spores and resistant cells to obtain a proxy of the composition of the fungal seed bank. This approach was first evaluated in selected species. The results obtained showed that DNA from fungal spores and from yeast is only obtained after the application of the lysis-resistant enrichment method, while mycelium is always lysed. After validation, we compared the total and fungal seed bank diversity in the polyextreme environment of the Salar de Huasco, a high-altitude athalassohaline wetland in the Chilean Altiplano. Environmental samples were collected from a salt flat and from microbial mats in small surrounding ponds. Both the lake sediments and microbial mats were dominated by Ascomycota and Basidiomycota, however, the diversity and composition of each environment differed. Members of the phylum Chytridiomycota were enriched in the lysis-resistant fraction, while members of the phylum Rozellomycota were never detected in this fraction. Moreover, we show that the community composition of the lysis-resistant fraction reflects the diversity of life cycles and survival strategies developed by fungi in the environment. To the best of our knowledge this is the first time that the fungal diversity is explored in the Salar de Huasco. In addition, the method presented here provides a simple and culture independent approach to assess the diversity of fungal lysis-resistant cells in the environment.