Antibiotic persistence in the environment, including water sources, is a significant concern due to the increasing prevalence of antibiotic-resistant bacteria. Tylosin is a common macrolide antibiotic used as a growth promoter in cattle, with 71% of feedlots administering it. Antibiotics such as tylosin, can persist as residual contaminants in surface water, groundwater, and wastewater. This poses a risk when these contaminated waters are used for irrigation. Such practice can result in the uptake of antibiotics by plants, which in turn may contribute to the development of antibiotic resistance in both human and living organisms. To determine the antibiotic uptake and its effects on crops, we spiked the nutrient solution with 2 levels of tylosin and grew lettuce (Lactuca sativa) in a nutrient film technique (NFT) hydroponics system. Two replicated experiments utilized the NFT hydroponic systems and included tylosin at concentrations of 5 mg/L and 10 mg/L, with reverse osmosis (RO) water as the control. Growth parameters were measured after 4 weeks at harvest, including aerial weight, head diameter, plant height, root weight, and root length. The results indicated that tylosin treatments had a negative impact with decreased root weight and length in the first experiment, whereas aerial measurements did not differ between treatments. The 10 mg/L tylosin treatment in the second experiment resulted in significantly wider head diameters and longer roots. Tylosin concentrations in lettuce leaf tissue were higher in both treatments compared to the control, although the 5 mg/L and 10 mg/L treatments showed similar responses. Water analyses throughout the experiments showed a decrease in tylosin concentration in the treated water over time, with no tylosin detected in the control treatment at any time. Multivariate correlation analysis revealed negative correlations between tylosin concentration and all growth parameters. These findings highlight the potential effects of tylosin on hydroponically grown lettuce and raise important considerations for using recycled or alternative water sources in hydroponic agriculture, particularly concerning food safety and crop productivity.
