| Based on the effective degrading strain X1 for chlorpyrifos,this paper through electrical and chemical transformation methods which import the plasmid pTR102 with LuxAB gene into chlorpyrifos-degrading strain X1.Aims to study the survival of transformants in different types and different treatment soils,and conduct an in-depth analysis on the property of Lux-X1 and X1 degraded chlorpyrifos and its products TCP,further delving into the effects on the colonization dynamics and transporting distribution for Lux-X1 of temperatures and humidity of abiotic factors in soil.The results are summarized as below.1.The strain of degrading bacterium X1 is not only efficient in chlorpyrifos,but also in its products as 3,5,6-TCP.Besides,the degradation effects on 200mg/L chlorpyrifos within 24 hours can reach up to 60.7%,while for TCP,the degradation rate is higher as 69.3%.2.By means of electric conversion and CaCl2 transformation methods,LuxAB gene has been successfully introduced into degrading strain X1 of chlorpyrifos and tag strain Lux-X1 been produced.According to the observation and comparison of light activity of the bacteria colonies,the success rates of electric conversion is greater than that of CaCl2 transformation method,and after resistance-free cultivation for 12 times in a row,the genetic stability of tag bacteria derived from electric conversionwas comparatively more stable than that of CaCl2 from transformation method.3.Lux-X1 and X1 witnessed a similarly consistent trend in terms of degradation dynamics on 200mg/L chlorpyrifos in different time,when it comes to 72 h,degradation rates of X1 was 79.25% for chlorpyrifos,tag bacteria fromelectric conversion was 72.82% and the counterpart from the CaCl2 transformation accounted for 68.96% respectively;simultaneously,20mg/L TCP gained from metabolism can be degraded completely.However,the capacityof degradation in chlorpyrifos was slightly different.In addition,since the introduction of exogenous DNA into X1,the degradation capacity of chlorpyrifos would not be affected,hence Lux-Xl strains could be released into the soil for testing and further restoration research.4.When the tag bacteria Lux-Xl was inoculated into sand,yellow-brown,steriled and non-sterile soil,survival data were as follows:sand soil>yellow-brown soil;sterilization soil> non-sterilized soil.To be more specific,the overall rule could be illustrated as a rapid decline of the living bacteria numbers during the previous 18 days after inoculation,followed by a slow decrease and later stability,with the plasmid retention rate decreasingwithin 0 to 30 days,afterwords,its trend experienced smoother and slighter fluctuations and remained still in soil in colonization.5.Under the condition as soil column at 10?,20?,30? and tag bacteria Lux-Xl existing in sand and clay,the higher the temperature,the slower the migration speed,precisely,with temperature changing,the corresponding migration rate was 10?> 20?> 30?.Nonetheless,within the environment of yellow-brown soil,the higher the temperature,the faster the migration speed,with its specific migration rate as 30?> 20?> 10? separately.From the above,it can be demonstrated that three various types of soil were likely to be affected by temperaturesto different degrees.6.Under the condition of soil column within 30%WHC,60%WHC,100%WHC and tag bacteria Lux-Xl in sand and yellow-brown soil,the maximum capacity of the field could arrive at 60%,making the bacteria strain moving fastest with its migration rate as 60%WHC>30%WHC>100%WHC;Under the circumstance of clay,its respective figures were 100%WHC>60%WHC>30%WHC.Thus,it was manifest that three different types of soil were liable to be influenced by humidity in a different sense.To be more exact,under the same environmental conditions and temperature or humidity,migration rate was displayed as sand > yellow-brown soil > clay. |
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