Tang Kai, Liang Yungang, Yuan Bo, Meng Jianyu, Feng Fuying
Laboratory for Environmental Microbiology and Biotechnology in Arid and Cold Regions, College of Life Sciences, Inner Mongolia Agricultural University, Hohhot, China.
College of Life Science, Inner Mongolia Normal University, Hohhot, China.
Front Microbiol. 2023 Aug 7;14:1074855. doi: 10.3389/fmicb.2023.1074855. eCollection 2023.
Biological soil crusts (BSCs) are distributed in arid and semiarid regions, and they function as important microhabitats for nitrogen fixation. The diazotroph community is critical for nitrogen fixation in BSCs and their subsoils. However, little is known about the key groups in different types of BSCs and subsoils in temperate semi-arid or arid deserts.
Here, we sampled three types of BSCs and their subsoils from the Inner Mongolian plateau, investigated the distribution characteristics of the diazotroph community by high-throughput sequencing, predicted keystone species using the molecular ecological network analyses pipeline (MENAP), and verified their close relationship with the available nitrogen (AN) content.
The results showed that available nitrogen content in BSCs was higher than that in subsoils in three different types of BSCs, and there were differences among seasons and according to the mean annual precipitation. The abundance of diazotrophs was higher in Cyano-BSCs, while diversity had no significant difference among BSCs and subsoils. Cyanobacteria and Proteobacteria, Nostocaceae and Scytonemataceae, , , , and were the dominant phyla, families, and genera, respectively. The dominant groups belong to Skermanella, Scytonema, and Nostoc formed the core diazotroph community in the three types of BSCs and subsoils, and each had a close relationship with AN.
These results indicate that diazotrophs in BSCs and subsoils had high diversity, and the core diazotroph communities have a close relationship with nitrogen fixation and that they may be the main contributor to nitrogen fixing in BSCs and subsoils in temperate deserts.
生物土壤结皮（BSCs）分布于干旱和半干旱地区，是固氮的重要微生境。固氮微生物群落对于生物土壤结皮及其下层土壤中的固氮作用至关重要。然而，对于温带半干旱或干旱沙漠中不同类型生物土壤结皮及其下层土壤中的关键类群，我们了解甚少。
在此，我们从内蒙古高原采集了三种类型的生物土壤结皮及其下层土壤样本，通过高通量测序研究了固氮微生物群落的分布特征，使用分子生态网络分析管道（MENAP）预测了关键物种，并验证了它们与有效氮（AN）含量的密切关系。
结果表明，在三种不同类型的生物土壤结皮中，生物土壤结皮中的有效氮含量高于下层土壤，且不同季节以及根据年平均降水量存在差异。蓝藻型生物土壤结皮中固氮微生物的丰度较高，而生物土壤结皮及其下层土壤之间的多样性没有显著差异。蓝细菌门和变形菌门、念珠藻科和伪枝藻科分别是优势菌门、科和属。优势类群Skermanella、伪枝藻属和念珠藻属在三种类型的生物土壤结皮及其下层土壤中形成了核心固氮微生物群落，且每种都与有效氮密切相关。
这些结果表明，生物土壤结皮及其下层土壤中的固氮微生物具有高度多样性，核心固氮微生物群落与固氮作用密切相关，它们可能是温带沙漠生物土壤结皮及其下层土壤中固氮的主要贡献者。
