Effect of zinc and benzalkonium chloride on Nitrosomonas communis and potential nitrification in soil

A bacterial contact assay is described which uses a chemoautotrophic microo rganism, Nitrosomonas communis (strain Nm2) to evaluate the biological effe ct of contaminated soils. The effects of two toxicants on the ammonium oxid ation activity of the autochthonous microbial population in the soil are co mpared with inhibition of the same biological response in the new monospeci es bioassay. Experiments were performed using soil samples dosed with organ ic and inorganic contaminants (benzalkonium chloride and zinc) to demonstra te the mode of operation and the sensitivity of the bioassay. The EC50 valu es of zinc and benzalkonium chloride were calculated to be 171 and 221 mg k g(-1) soil, respectively. The toxic response provided by the bioassay can t hus predict the effect of soil pollutants on the autochthonous nitrifying b acteria. (C) 2001 John Wiley & Sons, Inc.