Impacts of cadmium addition on the alteration of microbial community and transport of antibiotic resistance genes in oxytetracycline contaminated soil

Individual and combined contamination of oxytetracycline and cadmium inhibited nitrification by inhibiting ammonia oxidizers

“…Fresh soil (equivalent to 50.0 g dry weight) was pre-incubated at 40% water holding capacity in a 250 ml serum bottle for 7 days at 25°C in darkness before the incubation experiment. The levels of OTC and Cd addition were referenced to the residual concentrations in soils and animal manure according to the previous research ( Li et al, 2010 ; Afzal et al, 2019 ; Guo et al, 2021 ). Specifically, the addition of OTC at 0.1 mg·kg −1 could be conducted to explore the toxic effects in lightly contaminated soils.…”

“…Tang et al (2020) demonstrated that addition of heavy metals alone or Antibiotics and heavy metals commonly coexisted in the soil, thus making contamination more widespread and complex (Guo et al, 2018). OTC contained several O-functional groups, which could act as potential electron donors and complexation with metal ions (Guo et al, 2021;Zhu et al, 2022). The interactions between antibiotics and heavy metals affected each other's environmental behavior and toxicological effects (Zhao et al, 2013).…”

“…The tetracyclines such as tetracycline, oxytetracycline and chlortetracycline were widely applied to animal feed in many countries. All these contaminants tended to be excreted into the environment as part of animal excrement, such as manure and urine, and agricultural organic fertilizers ( Sarmah et al, 2006 ; Zhang H. et al, 2015 ; Cao et al, 2016 ; Li et al, 2019 ; Guo et al, 2021 ).…”

“…Besides, OTC has various functional groups, which are easily combined with soil cations or metal oxides, and thus could be adsorbed on the soil surface by cation exchange, hydrogen bond exchange, surface ligand chelation. Researchers found that the adsorption curve of OTC fit the Freundlich model, with adsorption rates close to 100%, indicating that the soil had high affinity for OTC ( Tolls, 2001 ; Mifflin et al, 2006 ; Pan and Chu, 2016 ; He et al, 2019 ; Conde-Cid et al, 2020 ; Guo et al, 2021 ). In addition, some studies found that only small portions of tetracycline were ingested by animals, and nearly 60%–90% of tetracycline was released into the environment, including mud, soil and water ( Liu et al, 2020 ).…”

“…Meanwhile, the levels of heavy metals and antibiotics in organic fertilizers were significantly higher than environmental background concentrations ( Zhu et al, 2013 ). It has been reported that metal contamination as long-term and widespread persistent selection stress could transmit antibiotic resistance genes (ARG; Baker-Austin et al, 2006 ; Guo et al, 2021 ).…”