SCREENING AND IDENTIFICATION OF SURFACTANT-PRODUCING PETROLEUM-DEGRADING BACTERIA AND THEIR REMEDIATION EFFICACY
The surfactant-producing petroleum degrading bacteria screened from the soil around the refinery were used to investigate the fermentation conditions of surfactant production and the remediation effect on the soil.A dominant surfactant-producing strain,numbered M-8,was selected based on blood plate and oil drainage circle experiments,and identified as Bacillus cereus by physiological and biochemical tests and 16S rDNA sequence analysis;the production of lipopeptide surfactant by strain M-8 was determined by TLC and infrared spectroscopy.To make the strain produce more surfactant,the Plackett-Burman and Box-Behnken experiments were used to optimize the fermentation conditions for more surfactant production.The experimental results showed that the surfactant production of the strain could reach(1.305±0.05)g/L at a pH value of 8.15,21.8 g/L of sucrose,12.33 g/L of phosphorus source,and 3 days of fermentation incubation.The remediation effect on petroleum-contaminated soil after 48 d of treatment was measured under simulated laboratory conditions,using petroleum degradation rate,dehydrogenase activity,and soil respiration intensity as the indicators.The results showed that the oil removal rate of the added strain group reached 91.23％after 48 days of treatment,and the soil dehydrogenase activity and respiration intensity of the added strain were much higher than those of the soil without added strain.
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