The Effect Of DBP On The Micro-ecology Of Wheat Rhizosphere And Non-rhizosphere Soil

As one of environmental endocrine disruptors,phthalates(PAEs)can severely harm the nervous system and reproductive system in humans.Some of these compounds have the potential to be "triple allergenic"(teratogenicity,mutagenicity and carcinogenicity)toxicity.The rhizosphere is the main channel for pollutants to enter the plant,which determines the transport of pollutants to plant roots,plant uptake,transport and metabolism.PAEs repeatedly applied would threaten microbial community structure and function in the rhizosphere soil,sustainable development of agriculture and human health.Currently,the effect of PAEs on functional diversity,community structure and soil enzyme activities in rhizosphere and non-rhizosphere soils in different growing seasons have not yet been reported.Thus,It is important to investigate the effects of PAEs on soil microbial ecology.In this study,we investigated the effects and toxic mechanism of DBP on soil microorganisms in rhizosphere and non-rhizosphere using Biolog ECO,high performance liquid chromatography(HPLC)and Illumina HiSeq platform sequencing technology.The main results were as follows:(1)Effects of DBP on soil microbial functional diversityAt seedling and jointing stages,soil microbial activity(AWCD)and homogeneity(McIntosh)in rhizosphere and non-rhizosphere soils were promoted by lower(10 mg/kg)and medium(20 mg/kg)DBP concentrations,while they wereinhibited by higher DBP concentrations.The enrichment(Shannon)and dominance(Simpson)in rhizosphere and non-rhizosphere soils were significantly promoted by DBP(p<0.05).During the whole experiment period,the microbial functional diversity in rhizosphere soil were higher than those in non-rhizosphere soil.The utilization pattern of carbon sources in rhizosphere and non-rhizosphere soil was altered by DBP.The main carbon sources of microbes was carbohydrates and amino acids in the control and DBP groups,respectively.The utilization rate of microbes to carbohydrates in the rhizosphere soil was significantly higher than that of non-rhizosphere soil(p<0.05).(2)Effects of DBP on soil enzyme activityThe lower and medium concentrations of DBP promoted the soil protease activity,but the high concentration of DBP had the role of inhibition to the activity.DBP had a inhibiting effect on ?-glucosidase and polyphenol oxidase.With the concentration increasing,the inhibition of DBP enhanced,and the inhibition rate to non-rhizosphere soil was higher.The soil dehydrogenase?urease and acid phosphatase activity were stimulated by DBP.The activity of enzymes in rhizosphere soil were higher than those in non-rhizosphere soil.(3)Effects of DBP on matuity rhizosphere soil's bacterial community compositionFor Illumina HiSeq platform sequencing,results showed that dominant bacteria in wheat rhizosphere soil were Proteobacteria?Bacteroidetes?Acidobacteria?Firmicutes and Gemmatimonadetes and so on.After DBP treatment,Sphingomonadaceae and Bacillaceae were induced,which could degrade aromatic compounds and have a stress-tolerance.(4)Degradation of DBP in wheat rhizosphere and non-rhizosphere soilThe concentration of DBP in rhizosphere soil is lower than that in non-rhizosphere soil.The main reason may be that root exudates and enzymes in plant roots stimulated the activity and biotransformation of rhizospheric soil microorganisms,which accelerated the degradation of DBP.MBP was the metabolite of DBP in rhizosphere soil and non-rhizosphere soils.With the increase of culture time,the concertrations of DBP and MBP decreased gradually in the soil.At maturity,DBP concentrations in rhizosphere and non-rhizosphere soil were about 0.15 mg/kg and no MBP was detected.