| Polycyclic aromatic hydrocarbons(PAHs)were easy to cause soil pollution and increase the possibility of adverse effects on human activities and ecological health because of its characters of high octanol-water distribution coefficient and low biological availability.Soil pollution of PAHs as a major environmental problem and the remediation of contaminated soil had been paid more attention.Fusant strain 14 is a high-efficiency PAHs-degrading bacterium by protoplast fusion between Sphingomonas sp.GY2 B and Pseudomonas sp.GP3 A.In order to further understand the degradation mechanism of F14 in the degradation of phenanthrene,the surface compounds changes of cell membrane in the process of phenanthrene degrading were studied from the perspective of microbial cell membrane in this study.Through laboratory simulation testing,the phenanthrene degradation characteristics and impact factors were researched.Soil enzyme activity and F14 growth were also analysed.In this study,we aimed to study the biodegradability of F14 for degrading soil PAHs,which provide the possible application and scientific foundation for F14 in soil The main results were as follows:(1)The phospholipid,lipid hydroperoxide,lipopolysacharide and the hydrophobicity of cell membrane of the F14 were related definitely with the degradation of phenanthrene.With the increase of the concentration of phenanthrene,the content of phospholipids and lipopolysaccharide were increased,when the concentration is greater than 150 mg/L,the phospholipids is reduced.Malondialdehyde content was increased with increasing concentration of phenanthrene.F14 was higher cell surface hydrophobicity,and the cell surface hydrophobicities of F14 are respectively 69.7%,65.2%.(2)Through single factor experiments,effects of various reaction parameters ondegradation of phenanthrene,such as the water content,the amount of inoculation and proportions of nutrient elements were exployed.The results showed that strain F14 had better degradation effect on phenanthrene in soil.In the condition of 2 mL of inoculation(concentration of 0.5 g/m L)and 5 mL for additive water volume(moisture content of about 50%)suits the growth of F14 best.In addition,the impact of C: N: P ratio to the degradation is not obvious.Under the condition of phenanthrene concentrations of 100 mg/kg about 30% of the phenanthrene was degraded.It is accepted that F14 in artificially contaminated soils are able to effectively metabolize phenanthrene and tolerant to the concentrations of phenanthrene 100 mg/kg.(3)To explore the biological reactivity in the phenanthrene degradation process,determined the catalase,polyphenol oxidase and dehydrogenase activity in soil,it showed that dehydrogenase and polyphenol oxidase activities are sensitive to the addition of phenanthrene,but the activity of catalase was not affected.In addition,F14 were capable to colonize in the soil and the number of F14 was changed with the degradation of phenanthrene.The F14 numbers in the phenanthrene contaminated soil were all higher than in the uncontaminated soils.(4)In order to test the feasibility of microbial remediation of soils contaminated with PAHs,F14 were inculated into PAHs polluted soil to operate microbial remediation experiment.The results indicated that total degradtion rate of PAHs was 42% in 60 d and degradation rates of low-ring(2 and 3 rings)PAHs were enhanced significantly.Average degradation rate of low-ring PAHs was improved by 12 pecentage points than treatment without F14. |
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