GLUFOSINATE TOLERANCE AND UTILIZATION BY SOIL AND AQUATIC BACTERIA

The in vitro sensitivity of 227 environmental bacterial isolates to th e organophosphinate herbicide glufosinate (phosphinothricin) was inves tigated. Although 38 strains (17%) were wholly resistant to the compou nd at concentrations of up to 3mM, growth of 84 isolates (37%) was inh ibited at concentrations of less than 1mM. Inhibition could be reverse d by supplementation of the minimal growth medium with glutamine, whil st glufosinate-resistant mutants arose in almost all sensitive isolate s at frequencies ranging from less than 10(-9) to greater than 10(-4). Such mutants were found to have glutamine synthetase levels on averag e ten times higher than the corresponding glufosinate-sensitive wild t ypes. Evidence for the utilisation of glufosinate as the sole phosphor us source by a mixed bacterial population was obtained and its utilisa tion as a nitrogen source by a Gram-negative isolate was demonstrated.