Application And Degradation Mechanism Of High Degradation Efficiency Bacterial Of DDT In Indoor Simulation Repair

In this study, we use 8 strains(DDT degrade ability) as subjects, improve its DR(degradation rate) by domestication, choose the top 3 of it, study on degradation characteristics, by orthogonal tests get the optimum degradation conditions, study on degradation pathway, immobilization them, optimum degradation conditions by orthogonal test and build mixed strains, simulated natural degradation conditions indoor,explore immobilized mixed strains degradation conditions of DDT contaminated soil.The results show that, DR of 8 strains increased from 31.23%, 24.50%, 20.68%,35.70%, 51.60%, 18.40%, 40.45%, 30.65% to 35.23%, 26.40%, 22.90%, 40.10%,55.60%, 19.50%, 46.23%, 36.80% respectively, the top 3 is strain 12-2#, 12-3#, 23#,best degradation conditions respectively: 32℃, pH=7.0, adding amount 6 mL, max DR40.10%; 34 ℃, pH=7.0, adding amount 8 mL, max DR 5.60%; 32 ℃, pH=7.0, adding amount 6 mL, max DR 46.23%. DDT degradation pathway of 3 strains: aerobic condition, by action of DDT 2,3-dioxygenase; cis-2,3-dihydrodiol DDT dehydrogenase;2,3-dihydroxy DDT 1,2-dioxygenase; DDT will open loop directly, resulting4-Chlorobenzoate eventually. Immobilization allows DR of 3 strains increased from40.10%, 55.60%, 46.23% to 54.46%, 70.07%, 61.98% respectively, best preparation conditions of immobilized beads of 3 strains: SA(sodium alginate) 2%, CaCl2 2%,acticarbon 6 g/L, bacteria 4 mL(OD600=1.0), CLT(crosslinking time) 8 h; SA 3%,CaCl22%, acticarbon 6 g/L, bacteria 4 mL(OD600=1.0), CLT 8 h; SA 2%, CaCl2 2%,acticarbon 6 g/L, bacteria 3 mL(OD600=1.0), CLT 8 h; immobilized beads reused 3 times,the DR won’t significantly lower(P > 0.05); after 45 d low-temperature storage, DR decreased 4.23%, 3.33% and 4.52% respectively, mixed strain build optimal ratio is1:3:2, the optimum condition of degradation: 32 ℃, pH=7.0, bacteria 8mL, max DR58.43%; optimum condition of mixed strains immobilized beads: SA 3%,CaCl2 2%,acticarbon 10g/L, bacteria 3mL(OD600=1.0), CLT 8 h; best degrading conditions: 32℃,pH=7.0, adding mount 10.0g, max DR 70.23%; under the indoor simulated conditions,the max DR is 49.99%.