Ammonifying Bacteria and Their Toxic Response to Combined Pollution of Glyphosate and Cadmium:Isolation and Identification. (English)

In order to investigate the effects of combined contamination of the typical pollutants, such as pesticides and heavy metals, on the ecological environment, the ammonifying bacteria, a common strain in nature, was selected as an experimental study object. The experiment was conducted with cultivated soil as the bacterial source, a strain of ammoniated bacteria (Z1) was isolated and screened, which was identified as Pseudomonas. It was showed that the ammonification rate reached 0.792 mg/(L•h) at 12 h, and the amount of ammonia nitrogen produced was up to 22.500 mg/L at 48 h. In the case of glyphosate (GLY) and heavy metal cadmium (Cd) being used as target pollutants, the binary mixture system (GLY plus Cd) was thereby designed by the direct equipartition ray method; by adopting the time-dependent toxicity microplate analysis method, the efffects of GLY, Cd and the binary mixture system on Z1 were respectively determined about the concentration-effect data at different exposure time; and toxicity interaction type and intensity of the components of GLY-Cd mixture were analyzed by fitting zeroing method. As a result of the experimental study, the toxicity of a single pollutant to Z1 gradually increased as its concentration went up, with the characteristics of concentration and time dependent toxicity. The toxicity of Cd to Z1 was always greater than GLY to Z1; the five rays (from R1 to R5) of the GLY-Cd mixture system were characterized with dependent toxicity in terms of concentration, time and component-ratio, and the toxicity interaction mainly appeared to be antagonism, and R3 had the highest dCA value (65.4%) at 8 h. In summary, the combined pollution of GLY and Cd reduced their toxicity and bio-availability in soil. [ABSTRACT FROM AUTHOR]

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