Meiting Ju

Purification and characterization of biosurfactant produced by Bacillus licheniformis Y-1 and its application in remediation of petroleum contaminated soil

In our previous research, a petroleum degrading bacteria strain Bacillus licheniformis Y-1 was obtained in Dagang Oilfield which had the capability of producing biosurfactant. This biosurfactant was isolated and purified in this work. The biosurfactant produced by strain Y-1 had the capability to decrease the surface tension of water from 74.66 to 27.26mN/m, with the critical micelle concentration (CMC) of 40mg/L. The biosurfactant performed not only excellent stabilities against pH, temperature and salinity, but also great emulsifying activities to different kinds of oil, especially the crude oil. According to the results of FT-IR spectrum and (1)H NMR spectrum detection, the surfactant was determined to be a cyclic lipopeptide. Furthermore, through the addition of surfactant, the effect of petroleum contaminated soil remediation by fungi got a significant improvement.

Isolation, identification, and crude oil degradation characteristics of a high-temperature, hydrocarbon-degrading strain.

In this work, a hydrocarbon-degrading bacterium Y-1 isolated from petroleum contaminated soil in the Dagang Oilfield was investigated for its potential effect in biodegradation of crude oil. According to the analysis of 16S rRNA sequences, strain Y-1 was identified as Bacillus licheniformis. The growth parameters such as pH, temperature, and salinity were optimised and 60.2% degradation of crude oil removal was observed in 5days. The strain Y-1 showed strong tolerance to high salinity, alkalinity, and temperature. Emplastic produced by strain Y-1 at high temperatures could be applied as biosurfactant. Gas chromatography analysis demonstrated that the strain Y-1 efficiently degraded different alkanes from crude oil, and the emplastic produced by strain Y-1 promoted the degradation rates of long-chain alkanes when the temperature increased to 55°C. Therefore, strain Y-1 would play an important role in the area of crude oil contaminant bioremediation even in some extreme conditions.