不同风化年限碳酸岩风化壳真菌群落结构特征

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

摘要:

【目的】岩生真菌是促进碳酸岩生物风化的重要推动者，研究黔中典型喀斯特区不同风化年限碳酸岩风化壳真菌群落结构特征有利于了解真菌对岩石的风化作用。【方法】选取位于黔中花溪区南部的废弃碳酸岩墓碑为调查对象，对不同风化年限碳酸岩风化壳进行采样，运用宏基因组测序方法对风化壳样品进行基因测序，并利用统计学方法对真菌群落结构特征及功能特征进行分析。【结果】18个风化壳样品中共获得1 087种真菌，分属于9个门、44纲、538属。不同样本之间真菌群落数量和组成差异较大，在碳酸岩风化过程中，子囊菌门（Ascomycota）始终为优势类群，平均相对丰度达到95%以上，随风化年限的增加呈现显著下降的趋势。Shannon指数和Simpson指数显示，碳酸岩风化壳真菌群落多样性随风化年限的增加呈现先减小后增加再减小的趋势。从所有样本中共检测出3 379 478个KEGG pathway level 3通路相关基因，主要与物质能量的代谢、运输等功能相关。与碳循环、氮循环和硫循环相关的主要微生物属于子囊菌门，随着风化年限的增加呈现下降的趋势。冗余分析（redundancy analysis，RDA）结果表明，三氧化二铁（ferric oxide，Fe₂O₃）、全氮（total nitrogen，TN）和全磷（total phosphorus，TP）是影响不同风化年限风化壳真菌群落结构演替的重要环境因子。【结论】碳酸岩的风化强度随风化年限的增加而增加，这相应增加了岩石表面微生境的形成，提供了物质累积的条件，为微生物特别是真菌的定殖提供了条件。不同风化年限碳酸岩风化壳真菌群落存在明显差异，碳酸岩表面真菌群落随风化年限的增加，其繁殖策略也在发生转变（从r-策略到K-策略）。

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.