Abstract

The effect of heavy metals (zinc, cadmium, chromium and lead) at concentrations 50, 100 and 500 μg/ml of the heavy metal salts on glyphosate utilization by some bacterial species isolated from rice fields were studied, the addition of lead (Pb), cadmium (Cd) and zinc (Zn) to the glyphosate mineral salt medium used in growing the Acetobacter sp. significantly (P < 0.05) increased the rate of glyphosate utilization as indicated by the increase in the growth of the organism and could be attributed to easy uptake of the metal-glyphosate complex by the organism. The growth ofPseudomonas fluorescens was enhanced in the presence of zinc in the glyphosate medium, when compared to its growth in the medium without the heavy metals. This was followed by lead, cadmium and chromium, respectively.

Key words: Glyphosate herbicide, utilization, metal-glyphosate complex.