Community structure of fungi in crust of carbonatite weathered for different time

Abstract:

[Objective] Lithogenic fungi play an important role in the biological weathering of carbonatite. It is of great significance for understanding the weathering effect of fungi on rocks to investigate the community structure of fungi in weathering crust of carbonatite weathered for different time in typical karst areas of central Guizhou. [Methods] The abandoned carbonatite headstones in the south of Huaxi District in central Guizhou were selected and the weathering crust of carbonatite weathered for different time was sampled, followed by metagenomic sequencing of the samples. Moreover, statistical methods were used to analyze the structural and functional characteristics of fungal communities. [Results] A total of 1 087 fungal species were identified from 18 weathering crust samples, which belonged to 538 genera, 44 classes, and 9 phyla. The number and composition of fungal communities varied greatly among different samples. During the weathering of carbonatite, Ascomycota dominated the fungi, and the average relative abundance was >95%. The abundance showed significant decreasing trend with the weathering. According to the Shannon index and Simpson index, the diversity of fungi community in the crust decreased first, then increased, and finally reduced with the weathering. A total of 3 379 478 genes related to KEGG pathway level 3 were detected from all samples, which were mainly involved in the metabolism and transportation of materials and energy. The main microbiota related to carbon cycle, nitrogen cycle, and sulfur cycle belonged to Ascomycota, which showed a decreasing trend with the weathering. The results of redundancy analysis (RDA) suggested that ferric oxide (Fe₂O₃), total nitrogen (TN), and total phosphorus (TP) were important environmental factors affecting the community structure succession of fungi on the crust. [Conclusion] The weathering of carbonatite intensifies over time, which allows for the formation of microhabitat on rock surface, thus the material accumulation, and colonization of microorganisms, especially fungi. There were significant differences in the fungal communities of carbonatite weathered for different time. Fungal communities on carbonatite surface also change from r strategy to K strategy with the weathering.

Key words:karst;dissolution;bioweathering;lithogenic fungi;succession