The Isolation And Identification Of Chlorpyrifos Degrading Bacteria And Its Effect On Soil Amendment With PGPR

Nowadays, soil pollution has become one of the hot topic of global environmental problems, while the pesticide pollution is the most common phenomenon existing in the soil pollution. Chlorpynifos is a kind of medium toxic organophosphorus pesticides, and it can be effectively applied to the prevention of agricultural and urban pests. Residues of chlorpynifos will cause a series of soil pollution. On the basis of relevant researches, some studies were carried out to screen the efficient chlorpynifos degradation bacterial strains, develop compound soil amendment and study the effect of soil amendment.11 chlorpynifos degradation bacterial strains were screened from Plant rhizosphere soil or gardening soil. After 16 S r DNA sequencing and BLAST, 11 strains were identified as Burkholderia sp.,Klebsiella sp., Raoultella sp. and Enterobacter sp..CD5 or CD7 strain could effectively degrade the chlorpyrifos both in the medium and soil. Potted experiment proved that CD5 or CD7 strain has promoting effect on plant growth and soil enzyme activity, however, the promotion effect of CD7 is more obvious.At the ratio of 1:1, CD7 and JD37 could promote plant growth and degrade about66.43% chlorpyrifos in the soil. Further study found that warmcast absorbed more mixed bacteria than the talcum powder did under the same condition of carrier dosage.After a month preservation at room temperature, the number of living bacterium still maintained about 4.81×107cfu/g.Carrier and soil, at the ratio of 1:1, could increase the plant growth, soil enzyme activities and soil microbial quantity.The whole genome sequencing and bio-informatics analysis of plant growth-promoting rhizobacteriua(PGPR) Pseudomonas aurantiaca JD37 showed that the strain was capable of plant growth, bio-control and colonization in plant rhizosphere. Related genes were found in the JD37 to prove its function, such as putative genes related metal resistance, temperature-shock, bacterial motility and attachment to plant rhizosphere. 31 secondary metabolism synthesis gene clusters were found in JD37, among which 35.48% had function.The compound soil amendment consisted of CD7 and JD37(at the ratio of 1:1)and wormcast. Data showed that applying soil amendment was helpful to promoteplant growth and better to maintain soil microbial quantity, meanwhile it improved the soil enzyme activity and so on. The concentration of chlorpynifos in different treatment was reduced to 238.98mg/L and 208.98mg/L, respectively.The experimental results showed that the compound soil amendment containing chlorpynifos degradation bacterial strains together with PGPR and wormcast had many different function, which have been proved by the whole genome sequencing and bio-informatics analysis. All these results may lay the foundation of applying this compound soil amendment to contaminated soil in future research.