Uptake of gentamicin, tylosin and oxytetracycline by lettuce and radish plants -

Abstract

Antibiotics are extensively being administered to livestock to promote growth and reduce illness. Studies have shown that antibiotics may be present in manure as the parent compound or their metabolites. Manure is used as plant fertilizer and a source of quality enhancement consequently affecting the environment. Research articles point out the potential human health risks and increased microbial resistance associated with the consumption of fresh vegetables grown in soil amended with antibiotic rich manure. In Lebanon, gentamicin, oxytetracycline, and tylosin are widely used in animal production. The aim of this study is to examine the ability of plant (lettuce and radish) in absorbing these antibiotics at four concentrations (0, 2.5, 5, and 10 mg-kg) from two growth media (manure amended soils and soil without manure) and investigate in their accumulation sites. A factorial pot experiment was conducted at the greenhouse of the American University of Beirut. The antibiotic analysis was accomplished using the enzyme linked immunosorbent assay (ELISA). The results showed that gentamicin accumulated in lettuce and radish leaves and roots. Tylosin accumulated in lettuce and radish roots but not in the lettuce leaves. Moreover, oxytetracycline was not absorbed by lettuce but it accumulated in radish roots. Among the three antibiotics gentamicin was the only antibiotic that was translocated to the lettuce leaves whereas the three tested antibiotics accumulated in the radish roots (edible part). In addition, manure enhanced the uptake of the three antibiotics by lettuce and radish. The obtained results indicated also, that increasing the concentration of the antibiotic in the growing media did not lead to a significant increase in the accumulation levels of antibiotics in plant tissues.