Uptake of the Plant Agriculture-Used Antibiotics Oxytetracycline and Streptomycin by Cherry Radish─Effect on Plant Microbiome and the Potential Health Risk

Abstract

Antibiotics are used to control certain bacterial diseases in plant agriculture. Understanding antibiotic uptake by edible vegetables after application and associated risks on plant microbiome and human health is critical. In this study, oxytetracycline and streptomycin, the two most commonly used antibiotics in plant agriculture, were applied to cherry radish via continuous soil drenching to study their translocations into plant tissues, influence on radish microbiome, and the potential health risk to mice. The results demonstrated that oxytetracycline induced hormesis in radish plants and both antibiotics were translocated into the leaves, fruits, and roots of radishes from the soil, with significantly higher plant uptake of streptomycin than oxytetracycline. Interestingly, the proportion of culturable oxytetracycline or streptomycin-resistant bacteria in the antibiotic-accumulated radish tissues was significantly higher than that in the antibiotic-free radish tissues, although both bacterial and fungal communities in different radish tissues were not affected by the accumulated antibiotics, demonstrating that antibiotic application could enrich antibiotic resistance in the plant microbiome. Feeding mice with antibiotics-accumulated radish tissues did not show significant effects on the weight and blood glucose levels of mice. Overall, this study provides important insights into the risk of using antibiotics in plant agriculture.

Overview of Direct and Indirect Effects of Antibiotics on Terrestrial Organisms

“…Recently, Yin et al [ 102 ] performed a microcosm experiment with cherry radish simulating an antibiotic treatment for controlling plant pathogens. Streptomycin (STR) or oxytetracycline (OTC), at 1.45 mg/kg each, were added at 21 days of plant growth.…”

“…The application of the antibiotic was repeated each 6 days for four times. At 44 days of plant growth most of the pots were sampled and eight were maintained with added antibiotic concentrations of 14.5 mg/kg each, in line with agricultural practices for large biomass plants [ 102 ]. The ABs did not affect radish growth, and OTC stimulated plant development.…”

Review on Biogeochemical Characteristics of Typical Antibiotics in Groundwater in China

“…In agriculture, antibiotics are heavily used in China and can be detected in nearby groundwater. The most used antibiotics in agriculture today are oxytetracycline and streptomycin, which are used to treat citrus "Huanglongbing" and plant pathogens in edible vegetables, such as bacterial wilt of tomatoes [73]. Unfortunately, antibiotics can contaminate groundwater, whether absorbed by crops and entering the food chain, or through sewage irrigation and fertilization.…”

The Underground World of Plant Disease: How Does Rhizosphere Dysbiosis Affect Plant Health Above-ground?

“…Management of bacterial spot disease on tomato is challenging due to limited host resistance, pathogen tolerance to copper bactericides, and the aggressiveness of the pathogen (Abrahamian et al 2019). streptomycin is an antibiotic that is labeled for use on greenhouse tomato production, which can be effective when target strains are sensitive (Abrahamian et al 2019) Since the 1950s, when streptomycin was licensed to combat the bacterial disease fire blight in apple trees, antibiotic use has expanded to other pathosystems, including bacterial spot disease in tomato and pepper plants and “Huanglongbing” on citrus trees (Kirchhelle 2018, Yin et al 2023). Despite its expansion in use, several concerns have been raised with antibiotic application in agriculture, such as the increase of antibiotic-resistant bacterial pathogens (Stockwell and Duffy 2012) in the environment and the impact on non-target pollinators and microbes (Chen et al 2019), contributing to the vacate EPA exemption of Streptomycin use in Florida’s Citrus orchards since December of 2023 (EPA 2023).…”