Abstract: Biological soil crusts (BSCs) are widely recognized as ecosystem engineers. To understand the role of BSCs in carbon cycling, we utilized metagenomic sequencing to analyze the microbial community and gene diversity in the soil attached to mosses (CRS) and the soil shaken off from mosses (BS) in the moss crust of Baijitan. The results showed that Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexi, and Bacteroidota were the dominant phyla in the mossy crusts of Baijitan. Notably, there was no significant difference in these phyla between CRS and BS. We identified ACAT/atoB encoding acetyl-CoA C-acetyltransferase as the most abundant gene associated with carbon fixation, and ACSS1_2/acs, which encodes acetyl-CoA synthetase and is involved in methane synthesis, as the most abundant gene related to methane metabolism. Furthermore, the abundance of genes in the microbial communities of mossy crusts did not correlate with their ecological importance. This study will contribute to enhancing the understanding of the metabolic pathway of microorganisms in moss crusts and the mechanism of soil microorganisms facilitating soil nutrient accumulation at the genetic level.

Key words: mossy biocrusts, microbial diversity, carbon fixation, methane metabolism, soil chemical property