Isolation,Community Structure Analysis And Characterization Of Biphenyldegrading Microbial Consortium

Organic toxic pollutants(OTPs)are persistent and highly toxic contaminants widely distributed in the environment,including polycyclic aromatic hydrocarbons,polychlorinated biphenyls,and organochlorine pesticides.Microbiological remediation is one of the main methods for removing OTPs from the environment.In this study,the natural consortium BP-W was isolated from oil contaminated soil with biphenyl as the sole carbon source.BP-W can degrade 99.88%of 1g/L biphenyl in 72h,and the fastest degrading rate was 0.9711 g×L^-1×d^-1 at 12h-24h.Compared with similar studies,the degradation efficiency is at a higher level.The microbial community structure of BP-W was analyzed by separation,identification and PCR-DGGE techniques,and BP-W was composed by Uncultured bacterium,Chryseobacterium sp.BP-1,Pseudomonas putida sp.BP-2,Stenotrophomonas sp.BP-3 and Achromobacter sp.BP-4.Uncultured bacterium plays a major role in the degradation of biphenyl,because any combination of the others bacteria cannot degrade biphenyl.The natural consortium BP-W also has good degradation ability for PAHs and PCBs.The degradation rates of 100 mg/L naphthalene,phenanthrene,n-Hexadecane and PCB77 for 5 days are 100%,97.54%,42.26%and 26.73%,respectively.The natural consortium BP-W has strong tolerance to degrading substrates,and the degradation rate of 10g/L biphenyl,2.5 g/L naphthalene and 2.5 g/L phenanthrene can reach23.49%,93.30%and 57.87%,respectively.In the degradation experiments with biphenyl,naphthalene and phenanthrene used as mixed substrates,BP-W might give priority to the use of naphthalene with simple structure and easy degradation,followed by biphenyl and phenanthrene.The metabolites for the degradation of biphenyl was analyzed by GC-MS.A small amount of benzoic acid was detected in the extracellular metabolite,and we did not detect any intermediate metabolites of biphenyl in the intracellular metabolite.It is speculated that BP-W metabolizes biphenyl to benzoic acid,and then excretes extracellularly.Finally,benzoic acid is completely mineralized by other bacteria.