摘要:放线菌作为干旱、半干旱环境中生物土壤结皮（Biological Soil Crusts，BSCs）组成的重要生命存在形式之一，不仅是潜在临床有用天然产物化学多样性的重要来源，也是该生态系统物质循环与能量流动的重要参与者。以腾格里沙漠东南缘广泛分布的藻结皮和藓结皮为研究对象，通过宏基因组测序比较分析两种BSCs放线菌种群的分布特征、组成及其潜在代谢功能。结果表明，腾格里沙漠东南缘藻结皮与藓结皮土壤微生物组主要形成以地嗜皮菌属、红色杆菌属、类诺卡氏菌属、游动放线菌属、芽生球菌属、链霉菌属、贫养杆菌属、糖丝菌属、土壤红杆菌属、假诺卡氏菌属、小单孢子菌属、康奈斯氏杆菌属、大理石雕菌属、小月菌属以及弗兰克氏菌属等为主要类群的放线菌群落结构，在两种BSCs类型之间各属分布存在差异。藓结皮中放线菌参与的氨基糖与核苷酸糖代谢、原核生物中的碳固定途径、丁酸代谢、丙酸代谢、丙氨酸/天门冬氨酸和谷氨酸代谢、甲烷代谢、2-羰基羧酸代谢、肽聚糖生物合成、淀粉与蔗糖代谢以及缬氨酸/亮氨酸与异亮氨酸降解显著高于藻结皮。藓结皮中地嗜皮菌属和红色杆菌属对相对丰度前10的代谢功能分类的贡献度显著低于藻结皮，而类诺卡氏菌属、芽生球菌属、贫养杆菌属、游动放线菌属、链霉菌属、假诺卡氏菌属和糖丝菌属等对这些功能的相对贡献在藓结皮中具有重要作用。这些结果可为全面、深入理解腾格里沙漠东南缘藻结皮与藓结皮放线菌资源多样性及其潜在功能多样性提供科学数据，也为理解放线菌在不同类型BSCs中的生态功能提供参考。



Abstract:As one of the significant life forms found in biological soil crusts in arid and semiarid environment, actinomycetes are not only important sources of chemical diversity in natural products that are of potential clinical value but also vital participators in the material cycle and energy flows in the ecological systems. Taking cyanobacteria crusts and moss crusts that are widely distributed in the southeastern Tengger Desert as research objects, metagenome sequencing was performed to compare and analyze the distribution characteristics, components and potential metabolic functions of the actinomycete population in two biological soil crusts. The results showed that the actinomycete community structure of the soil microbiome was mainly composed of the genera Geodermatophilus, Rubrobacter, Nocardioides, Actinoplanes, Blastococcus, Streptomyces, Modestobacter, Saccharothrix, Solirubrobacter, Pseudonocardia, Micromonospora, Conexibacter, Marmoricola, Microlunatus and Frankia. There were differences in the distribution of genera between the two biological soil crust types. The participation of actinomycetes in amino sugar and nucleotide sugar metabolism, glycolysis/gluconeogenesis, carbon fixation pathways of prokaryotes, butanoate metabolism, propanoate metabolism, alanine metabolism, aspartate/glutamate metabolism, methane metabolism, 2-oxocarboxylic acid metabolism, peptidoglycan biosynthesis, starch/sucrose metabolism, and valine/leucine/isoleucine degradation was significantly higher in moss crusts than that in cyanobacteria crusts. However, the contributions of Geodermatophilus and Rubrobacter to the top ten most abundant metabolic functions were obviously lower in moss crusts than that in cyanobacteria crusts. In contrast, the relative contributions of Nocardioides, Blastococcus, Modestobacter, Actinoplanes, Streptomyces, Pseudonocardia, and Saccharothrix to these functions was of great significance in moss crusts. The results provide the scientific data for a comprehensive and in-depth understanding of the diversity of actinomycete resources and potential functions in algae and moss crusts in the southeastern Tengger Desert and for understanding the ecological functions of actinomycetes in different types of biological soil crusts.





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