Combination of a crude oil-degrading bacterial consortium under the guidance of strain tolerance and a pilot-scale degradation test

Under the guidance of strain tolerance, a new combinationmethod for crude oil-degrading bacterial consortium was studied. Firstly,more than 50 efficient crude oil-degrading and biosurfactant producing bacteriawere isolated from petroleum-contaminated soil andwater in Tianjin Binhai New Area Oilfield, China. Twenty-four of them were selected for further study. These strains were identified as belonging Pseudomonas aeruginosa, Bacillus subtilis, Brevibacillus brevis, Achromobacter sp., Acinetobacter venetianus, Lysinibacillus macroides, Klebsiella oxytoca, Stenotrophomonas rhizophila, Rhodococcus sp. and Bacillus thuringiensis. A shake-flask degradation test revealed that 12 of these strains could degrade over 50% of 1% crude oil concentration in 7 d. Of these, 8 strains were able to produce biosurfactants. Furthermore, environmental tolerance experiments indicated that the majority of the strains had the ability to adapt to extreme environments including high temperatures, alkaline environments and high salinity environments. A mixed bacterial agent comprising the strains WB2, W2, W3 and HA was developed based on the environmental tolerance tests and subjected to the pilot-scale degradation test indicating that this bacterial agent could degrade 85.2% of 0.8% crude oil concentration in 60 d. Our results suggest that the application of this mixed agent could remediate crude oil polluted soils in saline and alkaline environments.