Effect of some pesticides on growth, nitrogen fixation and nifgenes in Azotobacter chroococcum and Azotobacter vinelandii isolated from soil

This study was designed to evaluate the effects of three pesticides (Imazetapir, Dimethoate and Bayleton 50) at the recommended concentration (in the field), on the growth of pure cultures ofAzotobacter chroococcum and Azotobacter vinelandii, on the amount of fixed nitrogen and nifgenes. Herbicide Imazetapir had no negative effect on nitrogen fixing bacteria, while Dimethoate and Bayleton 50 exhibited inhibitory effect on growth. Same effects were obtained on fixed nitrogen obtained when treated with studied pesticides. nifH1, nifH2, nifH3, nifU and nifV from A. chroococcum, and nifH, nifK, nifD, and nifM gene in A. Vinelandii were lost when pots were cultivated with wheat and treated with both Dimethoate and Bayleton 50, therefore, be deemed highly susceptible to them. While herbicide did not affect the nif genes, the bands on gel electrophoresis appeared as normal sample.   Key words: Azotobacter chroococcum, Azotobacter vinelandii, fungicide (Bayleton 50), herbicide (Imazetapir), insecticide (Dimethoate).