Isolation and identification of alkaline protease producer halotolerant Bacillus licheniformis strain BA17

Abstract

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).