Bioactive Screen For New Fungicides And Insecticides Using Microalgae And Luminescent Bacterium

In this paper, fungicides and insecticides were tested to build a kind of model organism for screening pesticides using three microalgae and luminescent bacterium Vibrio-qinghaiensis sp.nov.-q67 .Comparison of effects of seven solvents on growth of microalgae, then toxicity assessment of fungicides and insecticides with photobacteria acute toxicity test.The results showed as follow:1) Three microalgae could be used for screening fungicides and insecticides as model organism, Scenedesmus quadricauda was more sensitive than the other two microalgae and it was selected firstly as target organism during pesticides screening. Next was the" Chlorella vulgaris and Selenastrum capricornutum.2) The optimum combination of condition for cultivating S. quadricauda were liquid HB-4 medium, at 25±1℃, light intensity of 50001x/cm2, illumination continuous and cultivating for 96 hours. At 25±1 ℃, during continuous illumination, each growth rate of microalgae reached the highest value.3) The optimum biological determination index was absorbance value at 680nm, which could reflect well the growth rate of microalgae and was measured quickly and accurately.4) Comparison of effects between luminescent bacterium and S. quadricauda, Screen using luminescent bacterium was measured easy and quickly, but was hard to control.5) The result showed that screen pesticidal active using luminescent bacterium and S. quadricauda was coincidence ultimately.6) The toxicity of acetone and DMSO was the lowest and their EC50 value were 15200mg/L and 18200mg/L respectively The data indicate that acetone and DMSO would be suitable solvents to use in bioassays involving microalgae and luminescent bacterium because of their low toxicity, especially in acetone.