Isolation Of Dichloromethane-degrading Strain And The Reserach On Preparation Of Composite Microoranism Agent And Constructing The Genomic Bank

The activated sludge for the removal of dichloromethane was inoculated on a specific carrier and enriched via a fermentation process. Thus, the composite microorganism agent applied for dichloromethane degradation was successfully prepared. The microorganism agent can be used to facilitate dosing. The effect of several operating parameters, including pH, drying temperature, carrier proportion. The best microorganism agent(pH:7.0; drying temperature: 35℃; carrier of the proportion:85%: 10%: 5%)was obtained by the orthogonal experiment. The best rate of degration reached to 25.81%(800 mg/L dichloromethane, 168 h).The microorganism agent has good stability and can be stored at room temperature stability of 30 d of time, 4℃under save 60 d or longer and still maintain the removal efficiency of dichloromethane.From the orientation of the activated sludge acclimation, the separation of a dichloromethane-degrading bacteria was screened for strains of the morphologi- cal, 16SrDNA, and Biolog. The strain was identified as Lysinibacillus fusiformis, the reports about the strain with degradation of dichloromethane was not found in relevant literature, therefore, the strain can be considered as a new function of strain degradation of dichloromethane, named as WH22. The dichloromethane can be degraded 22.7% in the concentration of 800 mg/L system by WH22 after 168 h.The parent strain WH22 which can degrade the dichloromethane was isolated from factory activated sludge, and it was identified as Lysinibacillus Fusiformis .The strain was induced by ⁶⁰Coγand UV for increasing the degration rate. The best dosage of ⁶⁰Coγprocess is 0.5 kGy, and the best dosage of UV process is 100 s or 120 s(18 W,30 cm).Three of the highly effective dichloromethane degrading mutants were breeded. They were measured in the MSM culture, adding dichloromethane as the sole carbon and energy. With the condition of 800 mg/L dichloromethane, their degration rate were 66.2%, 52.9%, 2.1%,which were 191.63%,133.04%,129.52% higher than the original strain , respectively. Among the orthogonal test, temperature is the most important factor, the best temperature is 30℃. Desecend of 12.40%,11.05%,0.68% in the degration rate of the mutants were observed after 8 times of subculture, respectively. Therefore, the obtained mutants are stable strains that are worth to be studied further.The study try to construct the Genomic Bank of WH22, and obtained the appropriate Genomic DNA, the best system for restriction enzyme digestion was got by gradient concentration digestion. The vector pUC19 linear DNA was obtained by enzyme digestion .But finally, the transformant has not been found.