Methyl-?-Cyclodextrin Enhanced Microbial Degradation Of Pyrene And Benzo [a] Pyrene

Polycyclic aromatic hydrocarbons(PAHs)are a group of organic pollutants widely present in the natural environment.They are poorly water-soluble and fatsoluble,and are widely concerned by environmental workers due to their "threeprongedness." At present,it is generally believed that the use of microorganisms to degrade polycyclic aromatic hydrocarbons is the most effective way.In this paper,methyl-?-cyclodextrin / pyrene inclusion complex was prepared by saturated solution method and characterized by IR,UV,TG-DSC and so on.The mechanism of its inclusion and solubilization was discussed.When the preparation temperature was 25 ?,the yield was the highest.The characterization by infrared,ultraviolet and thermogravimetry showed that pyrene occupied the cavity structure of methyl-?-cyclodextrin and formed a stable inclusion complex,Pyrene dissolved in water increased to 7.36 mg / L.Polycyclic aromatic hydrocarbons,due to their extremely low water solubility,further reduce the efficiency of the use of indigenous degraders.In the study of microbial degradation of polycyclic aromatic hydrocarbons,screening of highly degradable bacteria is a key task for researchers.In this paper,pyrene as a PAHs as the sole carbon source,from the oil-contaminated soil enrichment efficient microbial flora.The bacteria were degraded PAHs by high-throughput sequencing.The proportion of Rhodanobacter,Pseudomonas & Mycobacterium accounted for 35.77% of the total number of bacteria,which could efficiently degrade high molecular weight PAHs.The degradation rate of pyrene reached 65.91%,which showed 100%,85.48%,51.92% and 50.45% respectively for naphthalene,phenanthrene,fluoranthene and benzo [a] pyrene.When MCD was added at a concentration of 10 g/L,the ability of microorganisms to pyrene was improved.A long-term PAHs-contaminated soil sample was enriched,isolated and purified as an efficient B[a]P-degrading bacterium.The strain was identified as Enterococcus faecalis by morphological observation and 16 S rRNA gene sequence analysis.B[a]P as the only carbon source,the strain 14 days on the 30 mg/L of B[a]P degradation rate of up to 66.35%;reaction system with MCD,will to varying degrees,the degradation of bacteria,when With the addition of 10 g/L,the biodegradation ability of B[a]P increased with the degradation rate as high as 71.22%.The study also showed that strain B8 had an efficient B[a]P-degrading activity at 1%-5% salinity when the pH was slightly alkaline,which provided the basis for the soil remediation of PAHs contaminated soil in salt environment.