Aims Biological soil crusts (BSCs) are widely considered critical for soil fertility in arid ecosystems. However, how microbial communities regulate the C and N cycles during BSC succession is not well understood. Methods We utilized GeoChip 5.0 to analyze the functional potential of bacteria and fungi involved in the C and N cycles of BSCs along a 61-year revegetation chronosequence. Results The normalized average signal intensities of different functional genes involved in C and N metabolism in 61-year-old BSCs were significantly different from those in younger BSCs and most functional gene subcategories and the corresponding dominant functional populations were derived from bacterial rather than fungal communities. Most C degradation genes (dominated by the starch-degrading gene amyA ) were derived from Actinobacteria (mainly Streptomyces ) in bacteria, but Ascomycota (mainly Aspergillus ) was the key population for lignin degradation (dominated by the phenol oxidase gene) during BSC succession. N cycle genes involved in denitrification (such as narG , nirK/S , and nosZ ) and N fixation ( nifH ) were mainly derived from Unclassified Bacteria , whereas genes involved in ammonification ( ureC ) were mainly derived from Streptomyces . Moreover, redundancy analysis showed that soil biogeochemical properties were closely related to bacterial and fungal functional gene structures during BSC succession. Conclusions These findings indicate that bacteria play a crucial role in the regulation of C and N cycles during BSC succession in arid ecosystems, while fungi perform supplementary degradation of lignin, and these communities can successfully stimulate an increase in C and N metabolism in soil during the later successional stages of BSCs.

中文翻译：

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干旱生态系统生物土壤地壳演替过程中，细菌和真菌对碳和氮循环的贡献不同

生物土壤结皮 (BSC) 被广泛认为对干旱生态系统中的土壤肥力至关重要。然而，微生物群落如何在 BSC 演替过程中调节 C 和 N 循环尚不清楚。方法 我们利用 GeoChip 5.0 分析了参与 BSC 的 C 和 N 循环的细菌和真菌的功能潜力，这些细菌和真菌沿着 61 年的植被恢复时间序列。结果 61 岁 BSCs 中参与 C 和 N 代谢的不同功能基因的归一化平均信号强度与年轻 BSCs 显着不同，大多数功能基因亚类和相应的优势功能群体来自细菌而不是真菌群落. 大多数C降解基因（以淀粉降解基因amyA为主）来源于细菌中的放线菌（主要是链霉菌），但子囊菌（主要是曲霉）是BSC演替过程中木质素降解（以酚氧化酶基因为主）的关键种群。参与反硝化作用的氮循环基因（如narG、nirK/S和nosZ）和固氮（nifH）基因主要来源于未分类细菌，而参与氨化作用的基因（ureC）主要来源于链霉菌。此外，冗余分析表明，土壤生物地球化学性质与 BSC 演替过程中的细菌和真菌功能基因结构密切相关。结论 这些发现表明，细菌在干旱生态系统 BSC 演替过程中 C 和 N 循环的调节中起着至关重要的作用，