Microbial diversity mirrors carbon stocks and emissions in soils under contrasting land uses in Brazil

Soils contain a great diversity of microorganisms. Edaphoclimatic characteristics and land use affect the biological diversity of the soil. The hypothesis of this study is that the land use influences the diversity of fungi and bacteria and is correlated with the stock and emission of carbon in the soil. The aim was to identify which land uses, among native forest, agriculture, pasture and eucalyptus, in the three biomes of the State of Mato Grosso do Sul, Brazil (Cerrado, Atlantic Forest and Pantanal), have the highest microbiological diversity and to understand this relationship with soil carbon emissions and stocks. Carbon stock was assessed by analyzing total soil carbon in the layers sampled (0-10, 10-20 and 20-40 cm) at 100 sampling points for each land use and biome, while carbon emission was assessed at the same points using an EGM 5 portable device. Soil samples were grouped into a composite sample for each use and biome for microbiological identification analysis. Bacteria and fungi were identified using the 16S rRNA sequencing method and ITS1/ITS2 PCR, respectively. Our findings reveal that the abundance and diversity of bacteria and fungi is influenced by land use and biome. Cerrado has lower carbon emissions and higher stocks, and a high incidence of beneficial microorganisms of the genera Metarhizium and Bacillus and pathogenic microorganisms of the genera Penicillium and Fusarium. Atlantic Forest biome has higher carbon emissions and lower carbon stocks, and a higher number of beneficial microorganisms of the Bacillus genus. There was a greater carbon emission and stock in the pasture, with a high number of Bacillus, low temperature and high humidity. Agriculture emitted less carbon and stored little, with the presence of Fusarium and a moderate amount of Bacillus.