Toxicity of metal compounds to luminescent bacteria and sensitivity differences of different luminescent bacteria

The inhibiting toxicity of five heavy metal compounds-HgCl2,Pb(NO3) 2,Cd(NO3) 2,K2 Cr2 O7 and NaAsO2-on the luminescence of three kinds of luminescent bacteria-Vibrio qinghaiensis sp.-Q67,Photobacterium phosphoreum and Vibrio fischeri-was investigated by use of the Microtox test.The EC50 s(Median Effective Concentrations) of the five metals were measured based on linear regression analysis.The results showed that the toxic effects of the heavy metal compounds on the three kinds of luminescent bacteria were different.The toxicity order among the five heavy metal compounds to Vibrio qinghaiensis sp.-Q67 was HgCl2 Cd(NO3) 2 NaAsO2 Pb(NO3) 2 K2 Cr2 O7.To Photobacterium phosphoreum the toxicity order was HgCl2 NaAsO2 Pb(NO3) 2 Cd(NO3) 2 K2 Cr2 O7,and to Vibrio fischeri the order was HgCl2 Pb(NO3) 2 Cd(NO3) 2 NaAsO2 K2 Cr2 O7.The research results are an important guide to determine the risk of different wastewaters.The choice of different luminescent bacteria depends on the kind of wastewater tested by the Microtox test.If unknown pollutants are present in the wastewater,several kinds of luminescent bacteria should be chosen to ensure the reliability of results by Microtox test.