Study Of Phthalate(DBP)Degradation Bacterium B2 Fundamental Repair DBP Contaminated Rhizosphere Of Cucumber Seedlings

Facilities agricultural soil phthalate(PAEs)pollution source is very extensive,such as agricultural residues,pesticides and fertilizers,living garbage and irrigation all can cause the soil pollution.This study restored the soil contaminated with DBP by vaccinating DBP degradation bacterium B2.Cucumis sativus L.cv Jinyan No.4 were sown in pots.When three true leaves fully opened,physiology,biochemistry,ultrastructure of seedling roots and soil microbial community diversity were examined.The main results were as follows:DBP produced obvious effects to antioxidant system of cucumber root.Cucumber antioxidant system can effectively resisted low DBP(30 mg·L-1 and 50 mg·L-1)treatments and decreased under higher levels(100 mg·L-1 and 200 mg·L-1)compared tothe controls.On the other hand,SOD and POD provided a better defense against DBP induced oxidative damage in the roots of cucumber seeding,compared to CAT.The productions of both malondialdehyde(MDA)and proline(Pro)were promoted while protein content and root activity were decreased under DBP stress.The antioxidant enzyme activity effectively decreased after bacterium B2 inoculated.Moreover,MDA and Pro content decreased,protein content and root activity improved significantly.Inoculation of DBP degradation bacterium B2 had a promoting effect on cucumber growth.Visible impact on the cytoderm,mitochondrion,and vacuole was detected according to TEM.Contents of starch grains and golgi apparatus were changed The higher concentration of DBP polluted,the more serious the cells damaged.While,inoculation of DBP degradation bacterium B2 could effectively reduced DBP toxicity on the cucumber root cells.Cloning 17 stripes of DGGE gel,via sequencing appraisalhomology comparison,identification results show a rich microbial diversity in the soil.There were mainly three types,including Bacteroidetes?Firmicutes and Proteusbacillus.Proteusbacillus was the dominant bacterial community of the sample,including alpha phylum deformation,beta phylum phylum and gamma deformation.After inoculation of DBP degradation Microbial biomass of BacteroidetesFirmicutes and Proteusbacillus in soil samples were increased,microbial Evenness of Proteusbacillus improved.The order of microbial diversity in inoculation of rhizosphere was soil>inoculation of soil>rhizosphere soil>soil.