FAT HYDROLYSIS BY BACILLUS SUBTILIS LIPASE AND SOME PROPERTIES OF THIS ENZYME

HASSAN, RAMADAN A.; HAUKA, FATHY A.; ISMAIL, ISMAIL I.; SHADY, TAWFIK S.M.

doi:10.21608/ejar.1999.326134

FAT HYDROLYSIS BY BACILLUS SUBTILIS LIPASE AND SOME PROPERTIES OF THIS ENZYME

Document Type : Original Article

Authors

¹ Department of Microbiology, and Agriculture Chemistry, Faculty of Agriculture, Mansoura University, Mansou‌ra, Egypt

² Agricultural Microbiology Research Department, Soils, Water and Environment Institute, Agricultural Research Center, Giza, Egypt

10.21608/ejar.1999.326134

Abstract

The best saturation for lipase precipitation by ammonium sulphate was found to be 0.8, which gave the highest yield, being 90.9% with specific activity and degree of purification of 70.1 p.mol FFA/mg protein/min. and 8.75 folds, respectively. By using 0.8 saturation of ammonium sulphate, pH 6.0 was found as the best pH value for enzyme precipitation. The yield of lipase at such pH value was 76.36%. The effects of pH and temperature on lipase activity varied with the substrate. The optimum pH was in the range of pH 7.9; the optimum temperature was in the range 40-50°C in case of olive oil which was the best tested substrate. The pH stability curve at 4oC showed no discontinuities and had a maximum between pH 6.0 and 8.0 at 1, 24 and 48 hrs. Also at 21-50°C, the residual activity reached 88.1% and 47.6%, respectively. Moreover after 48 hrs, the residual activity showed 71.4 and 35.7%. respectively. The enzyme lost very little activity between 30-50°C and was also quite stable at 60°C, but it lost activity very rapidly at 80°C. The hydrolysis of oils by Bacillus subtilis lipase was also studied and the degree of hydrolysis at 40°C reached after 24 hrs 92.11, 84.62 and 79.79%, for olive, palm and coconut oils, respectively.