Study Of Degradation Characteristics Of Microorganism Strains And Main Degradation Products For Chlortetracycline

Chlortetracycline(CTC),belonging to tetracycline(TC)antibiotic, was widely used inthe prevention and treatment of diseases of livestock and poultry.Due to Slowdegradation,CTC easily induced drug resistance bacteria in the environment,so the CTCresidue problem has already caused widespread concerns.Though CTC biodegradation hasthe advantages of environmental protection,low energy consumption and highefficiency,reports of CTC biodegrading characteristics are very few at home andabroad.Therefore,this paper analyzed biodegradation characteristics of three microorganismstrains to improve the CTC degradation efficiency.Variation characteristics of CTC indifferent water environment and types of biological degradation products wereresearched,thus provided a scientific basis for biodegradation and dispose of the CTCresidual waste in the environment.The determination of CTC methods were studied,the CTC residues were extractedwith EDTA-Mcllvaine buffer bounce.By using gradient elution,the peaks of CTC andrelated substances can be completely separated. In the range of1.0-1500.0mg/Lconcentration, the method shown that R2of CTC standard curve was0.9991, detection limitwas3.00ug/kg, recoveries were in94%-102%, relative standard deviation (RSD) was from2.02%to7.63%.Degradation characteristics of the strain LJ245and LJ302illustrated that LJ245wasable to grow well and degrade efficiently at100mg/L of CTC.At the same time,LJ245wasable to grow well and degrade efficiently at300mg/L of CTC.To LJ245and LJ302,theoptimal pH of was6,the optimum temperature was28-30℃and the optimal carbon andnitrogen sources were sucrose and peptone,maltose and peptone,respectively.Glucose andammonium chloride,glycerin and potassium nitrate were chosen as the carbon and nitrogensources.Bacteria Ochrobactrum SW-5was tolerated the CTC among200-600mg/L. ForSW-5,the optimal pH of was6and the optimum temperature was30℃.Strain utilizated thesugars and glycerol better.Analysis of degradation trends and variation between isomers of CTC in differentwater environment showed that,at the same temperature conditions, pH in the3.0-11.0range,with increasing pH,the half-life was significantly shortened CTC tendency.CTC inmore acidic conditions to turn4-epi-CTC(4-ECTC) more alkaline conditions into isomerCTC(ICTC);Under the same pH conditions, temperatures in the range of20-121℃,as temperature is increased,decreased half-life of CTC,while CTC and four kinds of trendsisomer to reduce.Select E.coli and Micrococcus luteus as indicator bacteria, study antibacterial ofCTC,4-ECTC,iso-CTC,TC,4-ETC.Determination of toxicity of different isomers showedthat CTC,4-ECTC and TC inhibit the growth of E.coli most greatly. CTC was found to bemost toxic, followed by4-ECTC and tetracycline when Micrococcus luteus was used as atest organism.For microorganisms,CTC and its isomer of different toxicity.CTC biodegradation process produced dechlorination-dehydration-desmethylsubstance(m/z=427),dechlorination-dehydration-demethylation-dedimethylsilane substance(m/z=369), and m/z=274substance which presumed to be an open loop substances.