Staphylococcus lipolyticus sp. nov., a new cold-adapted lipase producing marine species

Abstract

A cold-adapted lipase producing bacterium, designated SS-33T, was isolated from sea sediment collected from the Bay of Bengal, India, and subjected to a polyphasic taxonomic study. Strain SS-33T exhibited the highest 16S rRNA gene sequence similarity with Staphylococcus cohnii subsp. urealyticus (97.18 %), Staphylococcus saprophyticus subsp. bovis (97.16 %) and Staphylococcus cohnii subsp. cohnii (97.04 %). Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain SS-33T belongs to the genus Staphylococcus. Cells of strain SS-33T were Gram-positive, coccus-shaped, non-spore-forming, non-motile, catalase-positive and oxidase-negative. The major fatty acid detected in strain SS-33T was anteiso-C15:0 and the menaquinone was MK-7. The genomic DNA G + C content was 33 mol%. The DNA-DNA hybridization among strain SS-33T and the closely related species indicated that strain SS-33T represents a novel species of the genus Staphylococcus. On the basis of the morphological, physiological and chemotaxonomic characteristics, the results of phylogenetic analysis and the DNA-DNA hybridization, a novel species is proposed for strain SS-33T, with the name Staphylococcus lipolyticus sp. nov. The strain type is SS-33T (=MTCC 10101T = JCM 16560T). Staphylococcus lipolyticus SS-33T hydrolyzed various substrates including tributyrin, olive oil, Tween 20, Tween 40, Tween 60, and Tween 80 at low temperatures, as well as mesophilic temperatures. Lipase from strain SS-33T was partially purified by acetone precipitation. The molecular weight of lipase protein was determined 67 kDa by SDS-PAGE. Zymography was performed to monitor the lipase activity in Native-PAGE. Calcium ions increased lipase activity twofold. The optimum pH of lipase was pH 7.0 and optimum temperature was 30 °C. However, lipase exhibited 90 % activity of its optimum temperature at 10 °C and became more stable at 10 °C as compared to 30 °C. The lipase activity and stability at low temperature has wide ranging applications in various industrial processes. Therefore, cold-adapted mesophilic lipase from strain SS-33T may be used for industrial applications. This is the first report of the production of cold-adapted mesophilic lipase by any Staphylococcus species.