The Impact of Tetracycline on the Soil Microbiome and the Rhizosphere of Lettuce ( L.).

The impact of tetracycline on the soil and rhizosphere microbiome of lettuce was analyzed. Soil was collected from an agricultural field regularly fertilized with manure, and tetracycline was added at two concentrations (5 mg/kg and 25 mg/kg). In untreated soil, dominant bacteria included (43.17%), (17.91%), and (3.06%). Tetracycline addition caused significant shifts in the microbiome composition, notably increasing (22%) and favoring (low concentration) and (high concentration). decreased by 21%, possibly indicating antibiotic resistance development. An increase in , particularly , suggested a selection for resistant strains. In the lettuce rhizosphere, tetracycline-induced changes were less pronounced than in soil. remained dominant, but taxa like and increased in response to tetracycline. The rise in chitin-degrading bacteria might result from fungal overgrowth linked to the bacteriostatic effects of tetracycline. Pathogens such as , observed in the soil, were not detected in the lettuce rhizosphere.