Study On Screening,Degradation Mechanism And Degradation Products Of Heptachlor Degrading Bacteria

As one of the environmental hormone organochlorine pesticides(OCPs), pesticides, and popularity, in the world have been widespread production and use, with high toxicity and lipid soluble, enrichment, persistent and other features. Organic chlorine pesticides can migrate through the atmosphere, water body and other media, and can produce great harm to the ecological environment. Heptachlor as the widely used organochlorine pesticides, the environmental impact of the environment can not be ignored. Studies on the degradation of organochlorine pesticides in China and abroad are more mature, but mainly for the HCH and DDT, etc., few studies on the biodegradation of heptachlor.In this experiment, the microbial flora of Weihe was the source of the bacteria, and the bacteria were cultivated and domesticated under the condition of low temperature and anaerobic conditions. The single strain of heptachlor was isolated, and the single strain was degraded by single strain, and the dominant strain of heptachlor was selected, and the species of the strain were identified. To investigate the effect of different environmental factors on the degradation rate, and qualitative analysis of the degradation process, the degradation mechanism of heptachlor degradation bacteria and degradation products of heptachlor were obtained.The conclusions of this experiment are as follows:1. Taking natural microorganism in Wei he River as the source of bacteria, the pH was 12, and the temperature was 7, and the auxiliary carbon source was not added to anaerobic acclimation. By gradually increasing the concentration of heptachlor(increments 5ml, 1000μg//L) on the way, medium domestication, the microbial growth was good, and the bacteria was found to be degraded by heptachlor in the presence of low temperature and anaerobic conditions, and heptachlor could be the sole carbon source of heptachlor degrading bacteria.2. In this experiment, the domestication in maturation liquid isolated three heptachlor degradation strains(D1, D2, D3, respectively). At pH value of 7.0, the temperature is 12 degrees, heptachlor concentration was 1000μg/L, amount to 20 ml of anaerobic degradation of 10 days. The degradation rates of strain D3, D2 and D1 were 71%, 54% and 47%, respectively, and the degradation rate of D3 was the highest, and the dominant strain of this experiment was selected.3. By comparing the degradation rate of the dominant species under different environmental conditions, the degradation effect of the initial concentration of 20μg/L was the best when the pH was about 7. This experiment was due to the low temperature anaerobic, so the oxygen content and the temperature index of the environmental factors were not determined.4. Identification of dominant species, observation and analysis of the morphological and physiological characteristics of the dominant species. The advantage of this species is translucent milk white, smooth colonies, neat edge of the bacteria, and preliminary judgment for the bacteria Bacillus or bacillus.5. The dominant species in the process of degradation of heptachlor, through a series of chemical reactions of hydrolysis, elimination, substitution, addition, esterification and oxidation, remove chlorine from the structure and metabolism for other less chlorine alkyl compounds.The results showed that the natural microorganism in the river water of Weihe was the source of bacteria, and the dominant strain of the degradation of heptachlor could be domesticated and screened under the conditions of low-temperature anaerobic conditions.