Use Vibrio Qinghaiensis Sp.Q67 To Detect Acute Toxicity In Water

The research of luminescent bacteria toxicity test (LBT) can be ascended to 1980s abroad in developed countries. Now it has whole method and equipment for international standards.But there is a bug in the LBT system, the high sodium chloride concentration, 2% ,will affect the toxicity when they response with luminescent bacteria .There is almost no any natural luminescent bacteria found in freshwater. The exciting discover of Vibrio qinghaiensis sp.,type strain Q67 in Qinghai lake is the unique freshwater luminescent bacteria and a patent is possesed by Chinese scientist.It has advantage over traditional luminescent bacteria Vibrio fischeri T3 sp..But it has no unified method, and seldom related instrument is introduced entirely.There is short of reference and it is commonly used in freeze-dried bacteria. Many difficulties in the use of freeze-dried bacteria were found by researchers , for example, how to carry the powder under -20℃in long way ? And the outcome was bad when the hurt freeze-dried bacteria was used. It is not easy for many laboratories to make freeze-dried bacteria .So we resort to the primary character of Vibrio qinghaiensis sp. Q67, and explore the toxicity detection of As(Ⅲ),Cr(Ⅵ),Hg(Ⅱ),Cd(Ⅱ),Pb(Ⅱ) via freshly prepared bacteria suspension. We hope this work will be helpful to water toxicity detection in field without freeze-dried bacteria and only with limited instrument.Part 1. Basic research for using Vibrio qinghaiensis sp.Q67 to detect toxicity: The outcome indicates Vibrio qinghaiensis sp.Q67 is luminescent in pH 6~10, and best at pH 7.0. The luminescence has the same decreasing degree at temperature from 15 to 30℃. While the OD600 of bacteria suspension is from 1.7 to 1.8, the suspension is best in luminescence and shows good effect to PbCl2 exposure.The fixed OD600 can be easily repeatedly and will assure the toxicity effect.The toxicity test system constructed is based at temperature 25℃; pH 7.0; OD600:1.7 ~ 1.8; 50ul bacteria suspension added to 500ul ddH2O.Part 2. Single heavy metal toxicity to Vibrio qinghaiensis sp. Q67 : To explore arsenic, chromium, lead, cadmium, hydrargyrum acute toxicity to luminescent bacteria Vibrio qinghaiensis sp.Q67 at ambient temperature(25℃), we use freshly prepared freshwater Vibrio qinghaiensis sp.Q67(hereafter as Q67) as indicator organism to detemine the metal toxicants 50% effective concentration (EC50) on luminescence with RS9901 luminometor. According to regulation between luminescence and OD600 of Q67 suspension, suspension OD600 at 1.75 is selected to research. The relationship between reaction time and EC50 of metal toxicants was explored. Results: The EC50 of arsenic, chromium, lead, cadmium, hydrargyrum to Q67 was determined at ambient temperature .The EC50 of each toxicant and the toxicity sequence from small to large is: As(Ⅲ)(EC50 10.76 mg/L)