Unraveling Key Functional Bacteria across Land-Use Types on the Tibetan Plateau

Soil bacteria are vital to the modulation of soil carbon and nutrient cycling. However, the response of key microbiota and the metabolic potential of soil bacteria to tolerate disturbance have yet to be fully investigated across land-use types, especially in alpine ecosystems. Here, the potential of soil bacteria to conduct change to affect biogeochemical processes was evaluated across 4 paired natural land-use types (i.e., forest converted to shrubland or grassland, shrubland to grassland, and grassland degradation) on the Tibetan Plateau. Based on the FAPROTAX database, we found 574, 106, and 22 bacterial genera that were possibly related to the carbon, nitrogen, and sulfur cycles, respectively. Among the core and/or key genera involved in carbon and/or nitrogen cycles, Bradyrhizobium and Solirubrobacter were common before and after disturbance, whereas Bryobacter , Mycobacterium , and Arthrobacter were sensitive to disturbance. Disturbance had diverse effects on soil bacterial percentages in specific metabolic pathways. In particular, soil bacteria may lead to the decreases in carbon and nitrogen fixation, nitrite oxidation, and sulfate reduction under grassland degradation. Annual precipitation and plant Shannon index were important factors driving bacterial functional groups. These findings shed light on the substantial impacts of disturbance on bacterial metabolism, and suggest that some important bacterial taxa must be taken into consideration in policymaking and management strategies for the enhancement and maintenance of ecosystem functions.