Applications Of Degrading Bacteria Against Long-Residual Organochlorine And Organophosphate

The bioremediation of contaminated soil by HCH and DDT was studied in pot experiments by inoculating isolated strains of Sphingomonas sp. BHC-A and Pseudoxanthomonas sp. Wax against these two chemicals respectively under laboratory conditions. After 15 days, the flooding soil saw a degraded ratio of 82.7% and 73.9% of HCH and DDT respectively, whereas merely a spontaneous degrading ratio of 6.35% and 5.1% in soil with no inoculation:while the non-flooded soil witnessed a ratio of 73.1% and 68.5% respectively whereas only 5.4% and 4.3% in soil with no inoculation. So a remarkable degradation of the HCH and DDT could be reached in soil with varied moisture capacities by inoculating BHC-A and Wax and better effect in flooding than non-flooding. And the remnants of the two could be degraded effectively by means of the inoculation the two strains into soil of many a sorts.The germination of rice and rape seeds could be improved when soaked in degrading strain solutions of BHC-A and Wax. Beside of the stimulation of rice growth. BHC-A and Wax is also helpful to terminate the toxicity of HCH and DDT in rice. HCH and DDT possessed a relatively high inhibitive effect on microbes in tested soil, but the effect went downwards to some extent due to the adaptation of microorganisms to external environment. However, the effect of DDT was alternative, displaying a promotion to growth of soil fungi in a short time. BHC-A and Wax. when inoculated, could rescind the effect of pesticides on soil microorganisms and help with the recoveries of microbes. However, the two would suffer a detrimental effect from the competition of aboriginal microorganisms along with the time, causing a remaining impact of the remnants of pesticides on soil microorganisms to some extent.After the inoculation BHC-A and Wax into paddy plots contaminated by HCH and DDT for 4 months, the quantities of residue of HCH and DDT were 0.0012mg/kg and 0.013 mg/kg respectively, harnessing a degrading rate of 96% and 91.22%:in the meantime, there were 0.026mg/kg and 0.149mg/kg in the counterparts of zero inoculation, indicating a natural degradation rate of 17.46% and 14.86%. Plate colony counting indicated a rapid decline of the degrading strains along with time, ensuring a safe release to the environment because of the degrading bacteria being no the dominant populations in the soil. After the inoculation, the treatment saw a 0.0013mg/kgremnant of HCT and zero detection of DDT in brown rice, showing a degrading rate 85.9% and 100% as compared to the control. And a certain promotion to the biomass and yield of rice was observed by inoculating BHC-A and Wax-a rise of 4.57%、5.81% and 5.35% in the actual grain quatity of per ear. the 1000-grain weight and yield per acre. In addition of the promotion of the amino acid contents of rice, the strains could promote the assimilation of mineral elements (Zn. Cu. Mn etc) thus raising the quality of rice.In different soils, after the inoculation of BHC-A and Wax for 2 months, there was no HCH residues detected in Qihe3 and Dongyuan farms showing a degrading ratio up to 100%;while the ratios in Qihel, Qihe2. Zaozhuang and Jiaonan Haiqing were 83.02%, 85.37%,68.2% and 63.9% respectively in tested soil. the bioremediation effect of BHC-A to various tested soils followed in this order-paddy soil, purple sweet potato soil> Cereal soil> peanut soil> tea soil> pomegranate soil. And there was no DDT residue detcted in Qihe3. embodying a degrading ratio up to 100%:while the degrading rates in Dongyuan Dongyuan farms. Qihe2. Zaozhuang and Jiaonan Haiqing were 95.4%^ 92.59%、63.83% and 55.81%. The bioremediation effect of Wax to various tested soils followed in this order-- purple sweet potato soil> paddy soil> Cereal soil> pomegranate soil> tea soil. It suggested that the inoculation was effective in removing the HCT and DDT residue in rice and tea. but was ineffective in removing HCT in pomegranate.The degrading strains of Sphingomonas sp. Dsp-2 and Pseudomonas putida DLL-1 against chlorpyrifos and methyl parathion respectively isolated from contaminated soil in our laboratory was adopted as tested strains. In field conditions farming lands, after the inoculation of Dsp-2 for 15 days, the treatment enjoyed a further degrading ratio decline of chlorpyrifos of 76.7% as compared to the control. Thus it was effective in the degradation of chlorpyrifos in soil. There was no chlorpyrifos residues detected in soil after the inoculation of DSP-2 for 4 months. The inoculation of DLL-1 into contamined pomegranate soil for 2 months could bring in a further degrading ratio decline of methyl parathion of 51.6% as compared to the control. So the methyl parathion could also be degraded effectively. Meanwhile there was insignificant impact of DLL-1 on the degradation of the methyl parathion in pomegranate.The results showed that, the pesticides residues could be significantly reduced by means of the inoculation of some highly effective degrading microbial agents into soil and crops. And by this manner can it lay a foundation for the production of safe and sound agricultural products and supply a basis for the betterment of the ecological environment and human health.