Degradation Of Benzene Ring Pollutants By Inquilinus Sp. P6-4

Most of the pollutants with benzene ring in their molecular structure have aromatic properties.They are found in all areas of nature,exist in the productive activities of many industries at home and abroad,with certain toxicity.Therefore,It has become a hot issue in environmental governance to find a way to remove pollutants containing benzene ring,and it is of great significance to isolate the new benzene ring pollutant degrading strain and study its degradation characteristics.The P6-4 strain screened from tailings was taken as the research object,its classification status was determined based on 16 S r DNA sequencing,and its physiological and biochemical characteristics were studied.The degradation characteristics of pollutants were investigated by UV-Vis spectrophotometry.At the same time,the growth and degradation process of the strain were studied by kinetic methods,and the degradation pathways of the pollutants for strain was discussed by molecular biological technology.The results showed that:1.P6-4 strain was a gram-negative aerobic bacterium of the genus Inquilinus,grew on R2 A medium with a salinity of 1%-3% and citrate medium,and produced catalase,IAA and iron carriers.It had the function of dissolving phosphorus and fixing nitrogen.It did not produce amylase and acetyl methyl methanol while decomposing glucose.2.The P6-4 strain grew the best under the conditions of 30?,initial naphthalene mass concentration of 400 mg/L,p H 9.0,and 150 r/min.After 7 d of culture under the optimal degradation conditions,the degradation rate was 99.99%.The degradation rate for naphthalene by P6-4 strain under the optimal degradation condition can be expressed by the first-order kinetic model while the growth kinetics of P6-4 strain satisfied well to the logistic model.The final removal rate of chemical oxygen demand(COD)in the medium was 88.55%during the degradation process.The study of molecular biology revealed that the strain contained PAH(PAH-ring hydroxylating dioxygenase gene),HBHA(trans-o-hydroxybenzylidenepyruvate hydratase-aldolase gene),nah U(salicylate hydroxylase gene),S5H(salicylate 5-hydroxylase gene),CATA(catechol 1,2-dioxygenase gene),C230(catechol 2,3-dioxygenase gene),and GDO(gentisate 1,2-dioxygenase gene),and it was speculated that the P6-4 strain degraded naphthalene in two pathways: salicylic acid and and gentianic acid.3.The P6-4 strain grew the best under the conditions of phenol initial concentration of300 mg/L,30?,150 r/min,and p H 9.0.After cultured for 7 days,the degradation rate of phenol by P6-4 strain was 69.30%,and the growth process of strain P6-4 satisfied the logistic model.The specific primers of CATA and C230 genes were used for PCR amplification,and the results were positive.It was inferenced that the P6-4 strain had ortho metabolic and interposition degradation pathways.4.The degradation rate of 500 mg/L 2,4-dichlorophenoxyacetic acid(2,4-D)by P6-4strain was 61.79% after cultured for 7 days under 30?,150 r/min,and p H 10.0.The degradation rate could be described by the first-order kinetic mode,and the characteristics of each growth stage of the strain can be described by logistic growth model.The results showed that P6-4 strain could grow with benzene ring pollutants as the only carbon source,and effectively degrade benzene ring pollutants.It had a high degradation rate for naphthalene,phenol and 2,4-D,and had a significant COD removal effect on the culture medium.The degradation pathway of the degrading bacteria was preliminarily speculated through the amplification results of the degrading enzyme gene,which provided theoretical support for the degradation of pollutants containing benzene ring by the bacteria.