Abstract: A moderately thermostable and alkali-resistant lipase-producing strain named as H2 was isolated from peanut plantation soil using 2% benzene by Rhodamine B plate assay and shake flask fermentation. It was preliminarily identified based on morphological and physiological characteristics. Meanwhile, the 16S rDNA gene of the strain was cloned and sequenced. The physiological and biochemical characterization and phylogenetic tree based on the 16S rDNA sequence showed that the strain was highly homologous to Bacillus pumilus. The optimal culture medium for lipase production by the strain was composed of 3% peptone, 1% yeast extract, 0.5% NaCl, 1% olive oil, pH 7.0, and the optimal fermentation conditions of temperature, rotational speed and time were 28 ℃, 180 r/min and 48－60 h, respectively. The lipase produced under these conditions revealed the highest activity at 40 ℃ and pH 9.0. The lipase was stable over a broad range of pH (6.0－10.0) and temperature (35－50 ℃).

Key words: organic solvent tolerant, Bacillus pumilus, lipase, screening