CHARACTERISTICS OF HIGHLY EFFECIENT PETROLEUM-DEGRADING BACTERIA IN BIOREMEDIATION OF OIL-CONTAMINATED SOIL

The growth characteristics of 7 strains isolated from oil-contaminated soil in the north of Shaanxi province,as well as their degradation efficiency for various hydrocarbons,were investigated.The effect factors of these strains on oil degradation efficiency were revealed in a series of experiments.The results showed that isolated strains could degrade crude oil obviously.7 strains had high activity in 13 h and were easy to produce.7 strains could grow in paraffin wax,which indicated strains could degrade long chain hydrocarbon.Some of them(SY22,SY23,SY24,SY42 and SY43) were able to use short chain hydrocarbons and aromatic hydrocarbons as cultivation media,so they were preferential choice to be used for bioremediation of oil-contaminated soil.The pH values of 7.0 and 9.0 were optimum for SY21,SY42 and for SY22,SY23,respectively.NH4NO3 and oil concentrations from 1000 mg/L to 1500 mg/L were the optimum conditions for petroleum hydrocarbon degradation.Adding organic matter such as starch and glucose accelerated oil degradation of the SY22,SY42 and SY23 strains,which had ability in PAH degradation.The metal ions of Ni2+ and Co2+ in soil decreased the degradation efficiency of strains for crude oil,while the metal ions of Fe2+ and Mn2+ did not affect the oil degradation by strains.