BACKGROUND: The alkaline lipase production on vegetable oils as sole carbon source, its characterization and effect of different commercial detergents and surfactants on enzymatic activity from thermophilic Bacillus sp. DH4 was investigated. RESULTS: The organism grew on mannose, but the amount of lipase secreted was significantly less than on vegetable oils. This study identified a simple substrate for lipase production and established the utility of groundnut oil for increasing the lipase yield. The enzyme was compatible with various ionic and non-ionic surfactants as well as commercial detergents. Lipase activity was strongly inhibited by sodium dodecyl sulfate (SDS), but not by Triton X-100 or Triton X-114. The best assay conditions observed for this lipase was found to be pH 9.0 and 50 degrees C. The enzyme. was stable at alkaline pH and considerable activity was observed at pH 10 and it retained 93% of the residual activity at 60 degrees C. The lipase showed a novel property of marked activation at alkaline pH. Wash performance analysis of commercial detergent for removal of fatty stains improved upon addition of lipase. CONCLUSION: The production on cheap vegetable oils, novel properties and resistance towards various surfactants and tolerance to commercial detergents make this lipase a potential additive for detergent formulations. Significance and impact of the study: Bacillus sp. produces alkaline and thermostable lipase on cheap vegetable oils and its compatibility can find use in the detergent industry. (c) 2008 Society of Chemical Industry.