Characterization Of A Phenanthrene-degrading Microbial Consortium Constructed And Degrading Bacteria Isolated

Polycyclic aromatic hydrocarbons(PAHs)are a class of toxic environmental pollutants and one of the global Persistent Organic Pollutants(POPs),consisting of two or more fused benzene rings in various arrangements.PAHs are released into the soil,with their physicochemical properties of low solubility and structure of nonpolar,easily to absorbed by the biological.In this study,a novel aerobic microbial consortium for the complete degradation of phenanthrene was enriched from petrochemical contaminated soil in Puyang City,Henan Province,China.The consortium,named as ZY-PHE,could degrade more than 96%of 200 mg/L phenanthrene in a minimal salt medium in 3 days.Pyrosequencing analysis of the bacterial 16S rRNA gene suggested that Proteobacteria was the dominating phyla of ZY-PHE consortium representing 56.7%of the total number of detected sequences followed by Actinobacteria(21.7%),Deinococcus-Thermus(14.5%),Bacteroidetes(4.3%).Several abundant genera,Xanthomonadales(2.24%)Legionella(0.71%),Aeromicrobium(0.47%),Phyllobacterium(0.38%)and Cellulosimicrobium(0.31%),have firstly been detected in PAHs contaminated environment.The consortium has the ability to degrade other PAHs such as pyrene and fluorine by utilizing them as sole carbon and energy source.Further,consortium ZY-PHE exhibited an excellent pH adaptation and extensive temperature flexibility,indicating that this consortium could function well under a wide range of environmental conditions.Liquid chromatography-quadrupole-time-of-flight mass spectrometry assay revealed accumulation of few intermediate metabolites involving in phenanthrene degradation.The use of this bacterial consortium may be an attractive alternative for the bioremediation of polycyclic aromatic hydrocarbons in the environment.A phenanthrene degrading bacterium strain was isolated from ZY-PHE.According to the results of 16S rDNA analysis and pure colonies PLFA,the isolate was identified as Arthrobacter,and named as Arthrobacter sp.PHE152.Systematic studies were conducted on the degradation efficiency of phenanthrene by the strain PHE152,as well as the effect of initial phenanthrene concentration,temperature,pH,salinity and heavy metals on its ability to degrade phenanthrene.In the 200 mg/L initial phenanthrene concentration,28? incubated for 6 days,the strain PHE152 could degrade 90.58%of phenanthrene.The initial phenanthrene concentration has significantly influence on the initial degradation ability of the strain PHE152,and high initial concentration will lag growth in its degradation velocity.The optimum degradation temperature of the strain PHE152 is 28?,the optimum degradation pH is 7-8,the highest NaCl concentration the strain PHE152 could tolerate is 60 g/L.On the basis of the detected degradation metabolites of the strain PHE152,it is possible that this strain could degrade phenanthrene in the phthalate pathway and salicylic acid pathway.Both the consortum ZY-PHE and the phenanthrene-degrading strain PHE152 could be used for the bioremediation of PAHs contaminated encironments.