Uptake of Gentamicin, Tylosin and Oxytetracycline By Lettuce and Radish Plants.

Antibiotics administered to food-producing animals may be released in manure as the parent compound and/or their metabolites. When manure containing antibiotic residues is used as plant fertilizer it may become a potential risk for human health and the environment. In Lebanon, gentamicin, oxytetracycline, and tylosin are widely used in animal production. The aim of this study was to evaluate the ability of plants (lettuce and radish) to absorb these antibiotics from two growth media (manure amended soils and soil without manure) spiked with antibiotics at four levels (0, 2.5, 5, and 10 mg/kg) and also to trace the accumulation sites (roots and/or leaves). RCB greenhouse pot experiment was conducted and antibiotic analysis was done by ELISA kits. Gentamicin accumulated in both lettuce roots (12.7ng/g) and leaves (17.7ng/g) whereas in radish it accumulated in the roots (16.4ng/g) but was accumulated in the leaves at a higher concentration (31.51ng/g). Tylosin, only at the highest concentration assayed (10 mg/kg), accumulated in lettuce roots (11.23ng/g) with a limited translocation to the leaves (3.58ng/g); whereas in radish a higher absorption and accumulation of tylosin was observed in both the roots (56.6ng/g) and leaves (62.9ng/g). Oxytetracycline was not absorbed by lettuce but it accumulated in radish roots at a range of 1.83-3.98ng/g and was translocated to the radish leaves of the 5 and 10 mg/kg treatments reaching a concentration of 4.85-6.69ng/g. Manure enhanced the uptake of gentamicin and tylosin but not oxytetracycline. Keywords: Antibiotic uptake, pot experiment, radish, lettuce,