Potential functions of actinobacteria diversity in cyanobacteria and moss crusts in the southeastern Tengger Desert

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.