The Effect of Foliar Application of Selenium Fertilizer on Reduction of Antibiotics and Antibiotic Resistance Genes in Lettuce

To mitigate the dissemination and transmission of antibiotics and antibiotic resistance genes (ARGs) in both rhizosphere soil and vegetables, the experiment of growing lettuce (Lactuca sativa) in pots was conducted in a greenhouse by foliar application of selenium fertilizer. The self-developed biosynthetic nano-selenium and the commonly used sodium selenite were used as test selenium fertilizers in this study. The results show that the foliar application of selenium fertilizers could obviously reduce the contents of tetracycline, oxytetracycline, sulfamethoxazole, sulfadimethoxine, norfloxacin, and enrofloxacin in lettuces and their rhizosphere soil. The decrease rates of target antibiotics ranged from 38.1% to 100% in lettuce leaves, 13.4% to 100% in lettuce roots, and 3.8% to 71.0% in the rhizosphere soil. The foliar application of selenium fertilizers resulted in a marked decrease in the absolute abundance of ARGs in lettuces and rhizosphere soil. The decrease rates of target ARGs ranged from 11.8% to 87.0% in lettuce leaves, 5.9% to 100% in lettuce roots, and 1.5% to 78.3% in the rhizosphere soil. The application also significantly (P < 0.05) decreased the absolute abundance of mobile genetic elements (MGEs), which were the main factors in inhibiting the ARGs transfer within the soil-lettuce system. In general, the foliar application of biosynthetic nano-selenium had better effect on the reduction of antibiotics and ARGs in lettuces.