Metagenomic insights into seasonal variations in the soil microbial community and function in a Larix gmelinii forest of Mohe, China

The effect of seasons on the soil microbiome in a Larix gmelinii forest of Mohe, China, where winter temperatures are generally below - 40 degrees C, was evaluated with metagenomics analysis. Taxonomic profiling using sequencing information revealed that Proteobacteria, Actinobacteria, Acidobacteria and Verrucomicrobia were the dominant phyla in spring, summer, and fall, as were Bradyrhizobium, Chthoniobacter, Streptomyces, Acid Candidatus Koribacter at the genus level. Some species that were abundant in spring and fall greatly diminished in abundance in summer. Clusters of orthologous groups (COG) of proteins, carbohydrate-active enzymes (CAZy), Kyoto Encyclopedia of Genes and Genomes (KEGG) and NCBI databases were used to elucidate the function of diverse proteins and metabolites of the microbial community of L. gmelinii forest. COG analysis showed that fewer genes were detected in spring than in fall and summer, indicating that many soil microbes in the L. gmelinii forest were not tolerant to cold. Based on KEGG analysis, some pathways in the soil microbes were activated in spring and autumn and deactivated in summer. CAZy analysis revealed that most CAZy were more active in summer than in spring or autumn and were severely inhibited in the spring. Many functional pathways, proteins, and CAZy involved in the community changes were concerned with cold or heat resistance. Therefore, the soil in the L. gmelinii forest can be a valuable resource for further research on heat and cold tolerance of soil microbes.