Screening Of Phenanthrene-degrading Strain CFP312 And Its Solubilization And Biodegradation

Polycyclic Aromatic Hydrocarbons(PAHs)is one of the most important classification hydrophobic organic pollutants in the environment,and it is extremely harmful due to carcinogenicity,teratogenicity,mutagenicity,persistent presence and super bioaccumulation toxicity.Daily life is full of PAHs sources,such as “three wastes” emissions,the burning of domestic garbage,the waste gas generated by transportation,and the burning of fossil fuels,which are the common sources of PAHs,and humans and ecological environment have been deeply immersed in PAHs pollution enclosures.PAHs have become one of the main organic pollutants in environmental management.Currently,bioremediation is the most promising method of repairing PAHs.The screening of degrading bacteria is the first step in the bioremediation method,and the high-efficiency degrading bacteria of acquisition,which can greatly improve the degradation efficiency.The microorganism itself is affected by many environmental factors,so it is necessary to assist help from other substances to increase its degradation rate.Surfactants are the most popular substances to promote the solubilization of PAHs in the current research,and can also improve the bioavailability of PAHs.However,the mechanism of surfactant solubilization and biodegradation has always been one of the focuses of researchers.This study also attempts to illustrate this problem through a series of experiments.In this paper,a new idea of solubilization and biodegradation of cloud point system is proposed.By repeating the utilization of cells and cloud point system,the degradation efficiency of the strain is improved,and it is expected to reduce the time and cost in practical applications in the future.The experimental results of this study attempt to provide basic data and theoretical basis for bioremediation studies of PAHs contamination.The main research contents and results of the thesis are as follows:1?Screening of PAHs-degrading strains,analysis of physiological and biochemical characteristics,identification and preservation.The PAHs phenanthrene is a typical target pollutant,and the strain isolated and purified from the soil contaminated by the petrochemical products of Chenzhou was named CFP312.The strain showed white,round,small,slightly transparent,smooth and moist surface,easy to pick up,neat edge and luster on LB solid plate.The strain was found to be Moraxella osloensis sp.by 16 S rDNA sequence analysis and to have the function of degrading PAHs for the first time in our study.The strain CFP312 was preserved in Guangdong Microbial Culture Collection Center(GDMCC),Guangdong Institute of Microbiology,Guangdong,China.The preservation number is GDMCC 60595,and the GenBank accession number was MK283753.2?Analysis of degradation conditions.The effects of pH value,temperature,rotation speed,substrate concentration and time curve on the degradation of PAHs by strain CFP312 and the substrate utilization experiment were studied by UV spectrophotometry and high performance liquid chromatography(HPLC).The optimum degradation conditions for the degradation of phenanthrene were 37 ?,160 rpm,pH 8.0,and degradation for 48 h.The phenanthrene concentration was 400 mg/L,and the cell growth and degradation rate were the best.The strain CFP312 cannot utilize common carbon sources such as glucose and sucrose,but can exclusively utilize PAHs.3?Mechanism of solubilization and degradation of phenanthrene by Triton X-100 and?-CD.In order to explore the effects of surfactants on the degradation of strain CFP312 and its causes,the following experimental studies were carried out: screening of phenanthrene-degrading bacteria degradation system,effects of different concentration degradation systems on cell solubilization and degradation,effects of degradation system on cell growth,adhesion experiments of cells in NAPLs,effects of solubilization system on the distribution of phenanthrene in aqueous-nonaqueous phase and the adsorption and desorption of cells on crystalline phenanthrene.The following conclusions were obtained: Triton X-100,?-CD,TMN-3 and SL were screened out at the end of the experiment to enhance the degradation rate of PAHs by strain CFP312.Triton X-100 promotes the growth of strain CFP312 on a water-soluble carbon source at 1/2CMC,while ?-CD appears to promote the effect at5CMC;Triton X-100 and ?-CD have almost no effect on cell growth in liquid LB.The mechanism of degradation system Triton X-100 and ?-CD promoting the degradation of strain CFP312 may be related to cell adhesion,the distribution of phenanthrene in aqueous and non-aqueous phases,and cell elution.4?The exploration of a combination scheme for biodegradable phenanthrene with cloud point system and the reuse of cells.The cloud point elution solubilization biodegradation experiment mainly explored the related situation of continuous degradation of phenanthrene by repeated use of Sphingomonas cells in the cloud pointsystem.The following experiments were carried out: the effect of cell growth time on biodegradation,cells and cloud point system reuse experiments,cell and coacervate phase reuse experiments,cell alone reuse experiments and cell recycling protocol combination experiments.The main conclusions of the experiment are that the combined recycling scheme maximizes the biodegradation efficiency and provides the possibility of saving time and cost in future practical applications.