Effects Of DBP On The Community Structure Of Phyllosphere,Rhizospheres Microorganisms And Endophytes Of Vegetables

Widespread use of plasticizers in industrial production has led to increased reports of plasticizers in the environmental and plant,posing serious threats to human health and food safety.Dibutyl phthalate(DBP)is one of the most frequently detected plasticizers.In this experiment,Siyueman and Gaogengbai were used as test vegetables.The effects of DBP on the rhizosphere,phyllosphere microorganisms and endogenous bacterial community structure of vegetables were studied by pure culture and high-throughput sequencing.At the same time,the changes of enzyme activity and the endogenous hormones content in plants were studied by hydroponic culture under the stress of DBP.The main findings are as follows:1.The detection method of DBP in vegetables and soil was established.The DBP detection was performed by GC-MS.Under this test method,the correlation coefficient of the DBP standard curve was greater than 0.999,and the recovery rate of the soil and plants was above 85%.DBP was detected in vegetable roots,stems and leaves,and soil in the experimental group,and the DBP residue in soil was the highest.There were also differences in DBP residue between the two vegetables under the same treatment.For example,the DBP residue in the Gaogengbai root was 0.2 mg/kg under high concentration,but it was 0.46 mg/kg in Siyueman.2.In this chapter,the effect of DBP on the rhizosphere,phyllosphere microorganisms and endophytic bacterial community structure in Siyueman and Gaogengbai were studied using pure culture.After analyzing the diversity index of Siyueman,it was found that DBP treatments increased the diversity and abundance of the rhizosphere microorganisms and endophytic bacteria in Siyueman and Gaogengbai,and the low concentration of DBP had a more obvious promoting effect.The dominant phylum of the two vegetables were mainly Firmicutes,Proteobacteria,and Actinobacteria,but there were differences in the genus classification level.Under different treatments,there were significant differences in microbial community composition.For example,the relative abundance of Bacillus in Gaogengbai rhizosphere microorganisms increased with the increase of DBP concentration,while the opposite was true for Sporosarcina.3.In this chapter,the high-throughput sequencing technique was used to analyze the effects of DBP on the rhizospheric microorganisms and endophytic community structure in Siyueman and Gaogengbai.After analyzing the alpha diversity index of samples,it was found that the low concentration of DBP increased the bacterial diversity,while the high concentration of DBP inhibited the diversity.The dominant phylum of two vegetables were Proteobacteria,Firmicutes,and Cyanobacteria,but at the genus level,there were significant differences in bacterial community structure under different treatments.For example,the relative abundance of Pseudomonas in the control group was only 2.71%,while the relative abundance of Pseudomonas under G2 and G20 treatments reached 11.25% and 14.05% respectively.4.This chapter established the extraction and detection methods of four hormones: indole acetic acid,gibberellin,abscisic acid,and jasmonic acid.Under this extraction and detection method,the correlation coefficients of the standard curve were greater than 0.99,and the average recoveries were greater than 75%.After the plants were exposed to DBP stress,the activities of SOD,POD,CAT and other antioxidant enzymes were increased to remove the excess active oxygen.At the same time,the contents of indole acetic acid,gibberellin,and abscisic acid also increased with the increase of DBP concentration.Plants respond to adverse environments and play an important role in ensuring survival.