Abstract: A short rod shaped Gram negative surfactant-producing bacterium designated as SQ6 was isolated from the produced water from Daqing oilfield.The physiological and biochemical test showed that the SQ6 had the characteristics of Pseudomonas, and the 16S rRNA gene sequence analysis further indicated that the SQ6 had a similarity of 99.9% to Pseudomonas aeruginosa Growing on the mineral salts medium containing 2% glucose, the SQ6 decreased the surface tension of SQ6 zymotic fluid from 57.0 to 25.6 mN·m^-1within 24 hours. Under the conditions of high temperatures (121 °C for 30 min), high salinity (12% NaCl), and a wide range of pH, the SQ6 zymotic fluid could maintain a relatively stable surface activity, and its critical micelle concentration was 50 mg·L^-1. Thin layer chromatography (TLC) indicated that glycolipid was the main surface-active component presented in SQ6 zymotic fluid.

Key words: Straw pretreatment, Soil microbial biomass, Soil microbial respiration activity