| Dibutyl phthalate(DBP)as a plasticizer is widely used in plastic products.Due to the poor stability of plastic film,it can easily lead to the release of PAEs from plastic film.As a result,more and more DBP enter the soil,leading to agricultural pollution.In addition,chemical fertilizers,sewage irrigation and other improper use,also make a greate contribution to DBP content increasein soil.The DBP can be accumulated in the local crops in the contaminated soil,and then through the food chain into the human body,and human endocrine,nervous system and other organs of body.So the prevention and control of soil DBP pollution in farm land should be urgently needed.At present,the related research mainly focuses on the screening and characterization of DBP-degrading bacteria,and the research on the development of DBP-degrading bacteria multifunctional compound microbial preparation is less.Microbiological repair technology has the advantages of high efficiency,low cost,no secondary pollution,simple operation and good treatment effect.The aim of this study is to study a highly effective and synergistic multifunctional compound microbial preparation,which can improve the soil fertility and bioremediate DBP contaminated soil.The effects of multifunctional compound microbial preparation on DBP-contaminated soils and their effects on soil fertility were investigated by pot experiment.The effects of multifunctional compound microbial preparation on soil ecological security were investigated,and the effect of DBP microbial remediation was discussed.The potential application of this bacterial technology,not only provides scientific basis and technical support for the remediation of PAEs contaminated soil,but also provides reference for bioremediation of soil organic pollution.The main findings are as follows:Three strains of the plant growth-promoting bacteria(phosphate solubilizing bacteria P6,potassium bacteria K5 and nitrogen-fixing bacteria N1)were isolated from the soil.The phosphate solubilizing bacteria were identified as Sphingobium yanoikuyae,potassium bacteria were identified as Paenibacillus mucilaginosus,and nitrogen-fixing bacteria were identified as Enterobacter aerogenes.The determination of their own vitality,the N1 strain had a nitrogen fixation capacity of 14.56 mg/L,P6 was 28.44 mg/L and K5 was 22.61 ?g/m L.Three strains of bacteria and DBP-degrading bacteria(pre-laboratory screening,Pseudomonas sp.,named DNB-S1),were performed by plate scribing and shake flask test.And the results showed no antagonism between the strains and did not affect their viability.Mixed flora fermentation was carried out using fermentation medium for 48 h.The number of N1 was 5.3×108 cfu/m L,the number of P6 was 4.0×109 cfu/m L,the number of K5 was 5.0×109cfu/m L,the DBP-S1 number was 7.6×109 cfu/m L.The number of fermented strains was above 108cfu/m L,and the fermentation effect was good.Use the attapulgite,kaolin,humic acid as carrier materials to prepare the multifunctional compound microbial preparation which was reserved at room temperature.The number of viable cells in four kinds of bacteria can be maintained at high activity for 35 days.The optimal ratio of degrading bacteria and growth-promoting bacteria in multifunctional compound microbial preparation was performed.Those results showed thatthe best proportionof fdegrading bacteria and growth-promoting bacteria was 1:1(g:g),based on the effects of DBP degradation rate,soil fertility improvement(available nitrogen,available phosphorus,available potassium)and microbial diversity in soil.The effect of multifunctional compound microbial preparation on DBP contaminated Soil(20mg/kg)was conducted by greenhouse pot experiment.The effects of physiological indexes and quality,soil enzyme activity and soil fertility improvement on the economic crops were analyzed.In the process of cabbage growth,the content of chlorophyll of the multifunctional compound microbial preparation treated group was significantly higher than that of the pollution treatment group.The similar phenomenon was also found on MDA content.The results suggested that the application of bacteria significantly alleviate the toxic effects of DBP on cabbage.In addition,the dry matter accumulation in the cabbage was significantly higher than that in the control,and soluble protein content and vitamin C content were higher than that of the pollution treatment group by 24.93%,13.67%.The quality of cabbage was improved by the multifunctional compound microbial preparation.The urease,sucrase activity in soil played an active role with the application of the multifunctional compound microbial preparation,but the activity of catalase will not have a great impact.After application of the multifunctional compound microbial preparation,the contents of available N,available P and available K in soil were increased by 11.52%,11.01% and9.19%,respectively. |
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