Screening and identification of a highly lipolytic bacterial strain from barbecue sites in Hainan and characterization of its lipase

Abstract

A cheap and rapid screening method for isolation of lipolytic bacteria was established. A total of 145 lipolytic strains were isolated from oil-contaminated soil samples at barbeque sites in Haikou, China. Highly lipolytic strains were screened based on the formation of clearance zones on turbid solid media supplemented with emulsified peanut oil. One strain, C737-11, had the highest lipolytic activity and was further analyzed. This strain had physiological and biochemical characteristics that were similar to the genus Burkholderia. Phylogenetic analysis based on the ferric uptake regulator (fur) gene sequences located the strain to the clade of Burkholderia cepacia, Genomovar I, while resolution of the phylogeny based on 16S rRNA sequences was not good enough to distinguish Burkholderia species. The fermentation conditions were optimized and the optimal medium inducing or supporting lipase production was 0.5% glucose, 2% peanut oil, 2% peptone, 0.1% (NH4)2SO4, 0.1% K2HPO4·3H2O and 0.05% MgSO4·7H2O at pH 8.0. The optimal fermentation temperature was 37°C, and the best fermentation time was 72 h. Under these optimal conditions, lipolytic activity reached 10.5 U mL−1. The lipase produced by C737-11 was thermally stable and had an optimal reaction pH of 8.0 and an optimal reaction temperature of 37°C.