Comparative study on the petroleum crude oil degradation potential of microbes from petroleum-contaminated soil and non-contaminated soil

Comparative study on the petroleum crude oil degradation potential of microbes from petroleum-contaminated soil and non-contaminated soil was performed in the present paper. Three samples were employed to conduct the evaluation, of which two are from the petroleum-contaminated soil of Yanchang oil field, and one is from non-contaminated soil of Northwest University Campus, Xi’an. The bacterial plate counts in sample No. 1 of the petroleum-contaminated soil were 6.0 × 102 and the bacterial plate counts in sample No. 2 of the petroleum-contaminated soil were 4.0 × 103, while the bacterial plate counts in sample No. 3 of non-petroleum-contaminated were 6.0 × 104. Petroleum-degrading microbes were isolated from Bushnell Haas mineral salt medium and 16 bacterial strains and two fungal strains from PCS sample No. 1, five bacterial strains and one fungal strain from PCS sample No. 2, and 17 bacterial strains and one fungal strain from garden soil, respectively. For primary screening of potential petroleum-degrading microbes, 2, 6-dichlorophenol indophenol test was carried out and nine bacterial strains from PCS No. 1 and four bacterial strains from garden soil showed the potential petroleum-degrading activity. The petroleum degradation percentage of mixture of 13 bacteria was 47.57%, and it was higher than that of four fungi and the combined mixture (13 bacteria and four fungi). Study showed that the microbes isolated from non-contaminated soil had the good petroleum degradation potential.