Study On Mycorrhizal Bioremediation Of Mineral Oil Contaminated Soil

The degradation effect of ectomycorrhizal (ECM) fungi to mineral oil in pure culture or grow with a plant partner was studied in this paper. Oil degradation rate of symbiotic association under different conditions or with different methods of inoculation was compared. The optimum combinations of ECM fungi and some plants was screened for oil degradation, and degradation effect of ECM fungi associated with specific bacteria or fungi, azotobacter or VA fungi was discussed. The likely mechanisms of ECM fungi enhanced oil degradation and its influence to soil enzyme activity was also discussed.The results showed that 4 species of ectomycorrhizal fungi screened were able to degrade mineral oil. Their biomass and ability of oil degradation varies with the kind of culture mediums evidently. Their biomass and oil degradation rate would increase greatly with organic nitrogen source and a little glucose as starting carbon source in the culture medium. ECM fungal biomass fluctuates with the increase of oil concentration, ECM fungal biomass increased in lower concentration while decreased in higher concentration. The germination and growth of alfalfa and wheat seeds was inhibited evidently with increase of oil concentration, the dry weight of their root or radicel decreased regularly with the increase of oil concentration and can be used to judge the degree of oil pollution of soil.ECM fungi can infected some plants at highly oil-polluted (10000ppm) soils. The oil degradation rate, endurance and resistance of mycorrhiza-accreted plants enhanced evidently and can act sustainingly, oil concentration of soil decreased to normal level by some symbiotic associations in the next year. The results showed that optimum combinations were black locust with E2, bunge ash or Babylon weeping willow with E4. Pot and field experiment showed that degradation effect were better when plant inoculated with 4 species of ECM fungi together than with one or two species, and better in non-fertilizing treatment. Degradation rate enhanced but not markedly when inoculated ECM fungi in sterile soil compared with in unsteriled soil, and this may be due to the amount of microorganism and calatase and peroxidase activities increased in sterile soil.The effect of growth and oil degradation rate varied with species of plant when inoculated ECM fungi combined with specific bacteria or fungi, but both decreased compare with single inoculation when combined with azotobacter.Biomass of plant and oil degradation rate can be improved evidently when inoculated with ECM fungi, degradation rate increased by 32.3% than control at most. Whether endomycorrhizal plant or ectendomycorrhizal plant, the amount of bacteria in soil increased evidently in inoculated soil, this may be the main reason of ECM fungi facilitate oil degradation. Acid phosphatase and peroxidase activities increased and pyrogallic activity decreased markedly, suggest that ECM fungi inoculation can unproved fertility level of soil and the ability of plant to transform organic pollutant.The results provided basis for the application of mycorrhizal technology to bioremediation of mineral oil contaminated soil.