Isolation And Identification Of Luminescent Bacteria In Qinghai Lake And Toxicity Evaluation Of Luminescent Bacteria To Veterinary Drugs

Most luminous bacteria live in the ocean and can give out bioluminescence. luminousbacteria are often applied to the field of detecting environmental contamination because theyare sensitive to the contamination. Vibrio qinghaiensis, the only non-pathogenic, fresh waterluminous bacterium of the world was isolated from the body surface of Gymnocyprisprzewalskii by Pro.Wenjie Zhu who is working in South China Normal University. No studieshave isolated other luminous bacteria from the gut of G. przewalskii and other animals,sediments and various depths lake water in Qinghai Lake. There is no studies on theecological distribution characteristics of luminous bacteria in Qinghai Lake and aroundapplied water, which can reflect the quality of lake water.In this paper, luminous bacteria were isolated and identified from the samples of the gutand body surface of G. przewalskii, sediments and various depths lake water in Qinghai Lakeand around supplied rivers. The results showed the species and quantities of luminous bacteriain Qinghai Lake. On the basis of analysis on ionic compositions of water and sediments inQinghai Lake and around supplied river, whether there is optimum environment for luminousbacteria living in such environment were discussed, the correlations between luminousbacteria’s living and environmental factor were revealed, the relations between luminousbacteria’s diversities in mountain lake and contamination levels of water were discussed. Theresults can find new ways for evaluating the ecology and environment. Using luminousbacteria as indicator of bioassay for monitoring the toxic of11veterinary drugs used inTianshui district are simple, fast, and sensitive. The results not only provided scientific basisfor detecting water contamination technology based on luminous bacteria, but also resolvedthe scientific problem of luminous bacteria’s population distribution laws in mountain lake.The research findings laid a solid foundation for promotion and application of fresh waterluminous bacteria.Only16luminous bacteria strains were isolated from the body surface and the gut ofGymnocypris przewalskii in Qinghai Lake catchment. No luminous bacteria were isolatedfrom the sediments and various depths lake water in Qinghai Lake and around supplied rivers.The ionic compositions of water and sediments in Qinghai Lake and around supplied riverwere analyzed. The results showed that the major ions in Qinghai Lake are Na+-Cl-, and themajor cations are Na+> Ca2+>Mg2+>K+, and Daotang Lake is the second salinity river, BuhaRiver is slightly larger salinity than other rivers even though it is much lower than DaotangRiver. The major ions in Heima River, Buha River, Shaliu River and Haergai River are Ca2+,Mg2+, Na+, Cl-, and the highest ion of Ca2+is Heima River. 16strains luminous bacteria, the number is Q1-Q16, were isolated from the body surfaceand the gut of G.przewalskii. Strain Q1-Q16are gram-negative, rod shaped（0.5～0.8）μm×（1.0～1.5）μm）, polar flagella, motile, oxidase, catalase, nitrate reduction test, indole andV-P test-positive bacteria. Strain Q1-Q16ferment glucose and produce acid, secret amylase,gelatinase and DNase. The optimum growth temperature are20～25℃and optimum growthpH are8.5～9.0. Analysis of16s rDNA of Q1-Q16indicated that the isolate formed amonophyletic clade with the members of the genus Vibrio. The closest phylogenetic relativeamong the valid species was Vibrio anguillarum, with99.57%similarity. Tested by usingBiology Gen Ⅲ system, the strains could utilize30carbohydrates (12saccharides,5aminoacids,4carboxylic acids,2polymers and7others) of71carbohydrates under aerobic growthcondition. Based on the morphology, biochemical, physiological, the results of BiologyGenⅢ system identification and the result of analysis of16S rDNA sequence, these strainshad been identified as Vibrio anguillarum. The representative strain of a surface bacteriadesignated as Vibrio anguillarum strain Q1, and The representative strain of a gut bacteriadesignated as Vibrio anguillarum strain Q3, The optimum growth temperature is20～25℃and optimum growth pH is8.5～9.0.Vibrio anguillarum Q1and Q3were used as indicator of bioassay for monitoring theacute toxic of11veterinary drugs (0.85%NaCl is background solution,15min(sulfonamide30min) is consistent exposure, test instruments is BHP9511luminescence instrument).Relative luminosity and EC50were measured and acute toxic effects of11veterinary drugs toQ1and Q3were studied. The result showed that there is a better correlation between11veterinary drugs and Q1and Q3. Relative luminosity decreased with the increase ofveterinary drugs concentration.In15min exposure time, the toxity to Q1was in sequence of Ofloxacin> MequindocPremix> Enrofloxacin> Norfloxacin Nicotinate> Ceftiofur Sodium> Florfeniol>Lincomycin Hydrochloride> Sulfamomomethoxine> Streptomycin Sulfate> SulfadiazineSodium> Sulfa Trimethoprim Sodium. The toxity to Q3was in sequence of Ofloxacin>Mequindoc Premix> Enrofloxacin> Norfloxacin Nicotinate> Ceftiofur Sodium>Florfeniol> Lincomycin Hydrochloride> Streptomycin Sulfate> Sulfamomomethoxine>Sulfadiazine Sodium> Sulfa Trimethoprim Sodium. Different veterinary drugs has differentacute toxic to Q1and Q3.Quinolones had higher acute toxic to Q1and Q3than antibiotic. Thesulfa had the lowest acute toxic. Even the same class of veterinary drugs had different acutetoxic to Q1and Q3.