Among eleven aerobic thermophilic Bacillus strains, isolated from "El Carrizal" hot springs in Veracruz, Mexico, Bacillus thermoleovorans CCR11 (EMBL # AJ536599) was selected for lipase characterization because of its high lipase specific activity. Lipase was purified by dialiltration (polyethersulfone ultratiltration membrane co500,000), and preparative isoelectrofocusing. The lipase had a relative molecular mass of 11 kDa (the lowest M, reported), although it formed higher molecular weight aggregates in native form. The optimum catalytic conditions for Bacillus. thermoleovorans CCR11 lipase were 60 degrees C and pH 9-10. Hg2+, PMSF, SDS, Tween 80 and Tween 20 had an inhibitory effect on lipase activity, whereas Ca2+ salts and Triton X-100 increased it. Lipase activity was compatible with the presence of organic solvents, except for butanol. Lipase showed a notable preference for C6-C10p-nitrophenyl esters, with the highest activity toward p-nitrophenyl caproate (C10). Lipase stability in the presence of organic solvents, as well as in acidic and alkaline pHs and at high temperatures makes it a good candidate for its application in non-aqueous biocatalysis. (c) 2005 Elsevier Inc. All rights reserved.