MP5 Agrochemicals and Pesticides
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(AGA-1117-733643) Influence of two antibiotics on glutathione s-transferases activity in Maize and Pinto beans.

Farkas, M¹, Berry, J¹, Aga, D¹, ¹ State University of New York at Buffalo, Buffalo, New York, United States

ABSTRACT- The common agricultural practice of using livestock manure as cropland fertilizer can introduce non-metabolized antibiotics, excreted by treated animals, into the soil. A preliminary study was conducted to determine the effect of two common veterinary antibiotics, flavomycin and chlortetracycline, in maize (Zea maize) and pinto bean (Phaseolus vulgaris) plants. Two sets of each plant species were grown and transplanted in two separate soil pots: one in soil containing 20 ppm of the test antibiotic, and the other in antibiotic-free soil (control). After thirty days, the plants were harvested and total protein was extracted from the roots and leaves. The total protein was subjected to sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Clear differences were observed in the silver-stained banding patterns of total protein from antibiotic treated versus untreated plants. Of particular interest was a sharp increase in the intensity of bands within the size range of 25-30 kDa, indicative of an induction by antibiotics of plant glutathione s-transferases (GSTs). A GST activity assay using 1-chloro-2,4-dinitrobenzene as substrate revealed an increase in GST activity, relative to the untreated control. Antibiotic-treated soil samples, incubated with and without growing plants, were analyzed for antibiotics after 30 days of application using liquid chromatography/mass spectrometry (LC/MS). Antibiotic concentrations were decreased ten-fold in soils that supported plant growth. These results suggest uptake of the antibiotic from soil by maize and pinto beans, and implicate induction of GST as a potential mechanism used by these plants to detoxify the antibiotics.

Key words: glutathione s-transferase, chlortetracycline, flavomycin