| Phenanthrene degrading bacterial strains named F10a, F4a and B2b, pyrene degradingbacterial strains named B1, TB3 and B4 were isolated from petroleum contaminated soils.The biological characteristics of these bacteria strains are studied. F10a were identified asBacillus sp, Pseudomonas spp., B2b and B1 were identified as Azomonas spp., F4a, TB3and B4 were identified as by its morphological and biochemical characteristics. Twobacterial strains F10a and B4 were chosen to be used in this research.The degradation potential of phenanthrene by bacterial strain F10a was examined. Theeffects of salinity, pH, different initial phenanthrene concentrations and the addition ofdifferent heavy metal ions on degradation potential were investigated. Results showed thatthe degradation rate of phenanthrene (50 mg·L-1) were 98.12％after 27 hours in rotaryculture and 98.47％after 84 hours in static culture at 28℃. The degradation rates ofphenanthrene (100 mg.L-1) and phenanthrene (200 mg.L-1) were98.15％and 99.6％after 48h and 84 h culture. The degradation rates of phenanthrene were almost the same when pHwere 4, 6 and 8. The growth of F10a were inhibited when pH was 10. Cr6+(50 mg.L-1) wastoxic to the bacterium strain, Cd2+(100 mg.L-1) and Cu2+(50 mg.L-1) could inhibit thegrowth of strain F10a in some extent, Zn2+(100 mg.L-1) and Pb2+ (200 mg.L-1) had nosignificant influence on the growth. A significant positive relationship was found betweenbacterial growth and the phenanthrene degradation.The degradation of pyrene by bacterial strain B4 was examined. The effects of salinity,pH, heavy metals and the addition of glucose or salicylic acid on biodegradation potentialwere also investigated. The results show that, the bacterial strain B4 strain B4 had apotential of pyrene degradation, the degradation rate of pyrene was 91.70％as the pyreneconcentration was 50 mg.L-1. A significant positive relationship was found betweenbacterial growth and percentages of pyrene degradation. The bacterial growth was inhibitedwhen pH was 4 or salinity was 8％. Cd2+(100 mg.L-1) was toxic to the bacterial strain, Cu2+(50 mg.L-1) could partially inhibit the growth of strain B4, Zn2+(100 mg.L-1)andPb2+(200 mg.L-1) had no significant influence on the bacterial growth. The degradation rateof pyrene could reached 95.55％when salicylic acid (50 mg.L-1) was co-existing withpyrene.IAA and siderophore were excreted by bacterial strains F10a and B4, which couldstimulate the growth of plants. Effects of bacterial strains F10a and B4 on the growth ofmaize and PAHs (phenanthrene and pyrene) degradation in PAHs contaminated soils wereinvestigated by pot culture experiment. Results showed that, in phenanthrene contaminatedsoil, the biomass of maize with strain F10a or B4 inoculated were higher than that ofnon-inoculated treatments. In pyrene contaminated soil, the results were similar with'thephenanthrene contaminated soil. In phenanthrene-pyrene combined contaminated soil, thebiomass of maize between strain F10a and B4 inoculated treatments and non-inoculatedtreatments showed no significant difference. By using the technology of microbial-phytoremediation, The dissipation rate of phenanthrene in phenanthrene contaminated soil was72.39％, the dissipation rate of pyrene in pyrene contaminated soil was 60.62％, thedissipation rate of phenanthrene was 57.25％and The dissipation rate of pyrene was55.01％in phenanthrene-pyrene combined contaminated soil. The activities of catalase andpolyphenol oxidase in soils which maize grown were much higher than that of control.There was no significant difference between inoculation and non-inoculation treatments onthe activities of catalase and polyphenol oxidase in soils which maize grown. The bacterialstrain F10a and B4 could colonize in maize rhizosphere. The number of microbes inrhizosphere soils of maize was also investigated. The number of bacteria was stable, thenumber of fungi was decreased, and the number of actinomycetes was increased.
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