Effects of Chlortetracycline on the Growth of Eggplant and Associated Rhizosphere Bacterial Communities

The widespread use of tetracycline antibiotics in the poultry and cattle sectors endangers both human health and the terrestrial ecosystem. Chlortetracyclines (CTCs), in particular, have been proven to affect soil microorganisms in addition to plants in the terrestrial ecosystem. In order to assess the effects of CTC on soil properties, eggplant growth, and soil microorganisms, a potted experiment was carried out in this study. CTC significantly reduced the levels of ammonium nitrogen (NH4+-N) and nitrite nitrogen (NO2--N) in soil. Meanwhile, the eggplant's growth was clearly hampered. CTC dramatically and dose-dependently lowered the fluorescence parameters except the quantum yield of non-regulated energy dissipation (phi NO). Rhodoplanes and Cupriavidus, which were involved in N cycle, were enriched by 10 mg/kg CTC, according to results about different microorganisms at the genus level. Flavisolibacter was reduced by 10 and 50 mg/kg CTC, while Methylosinus and Actinocorallia were enriched by 250 mg/kg CTC. Redundancy analysis highlighted the profound impact of CTC on the soil microbial community, where strong correlations were observed with soil potential of hydrogen (pH), nitrate nitrogen (NO3--N), and NO2--N. These findings demonstrated the interdependence between the microbial community and soil characteristics, with CTC primarily affecting the microbes responsible for nitrogen cycling. Consequently, chlortetracycline poses potential hazards to both eggplant plants and the soil microbes in eggplant cultivation soil.