An alkaline protease producer Bacillus licheniformis strain was isolated from Van Lake in Turkey. The strain is Gram positive, aerobic, motile, sporulating rod-shaped bacterium. Spores were ellipsoidal and positioned central in nonswollen sporangium. The cells were able to grow well at a pH range of 5.7-10. The optimal growth temperature was found to be 37 degrees C. Growth at a wide range of NaCl concentration (from 0 to 20%) showed that BA17 is halotolerant. Main fatty acid composition of BA17 was anteiso-C15:0 and iso-C15:0. The strain was presumptively identified as B. licheniformis according to 16S rDNA gene sequence analysis. The most appropriate medium for the growth and protease production is composed of 0.5% yeast extract, 0.5% NaNO3, 0.02% MgSO4 center dot 7H(2)O, 0.1% K2HPO4 and 0.5% maltose, The optimum temperature and pH of the alkaline protease of strain BA17 were found to be 60 degrees C and pH 11, respectively. The activity was completely lost in the presence of PMSF, suggesting that the preparation contains serine-alkaline protease(s).