Detection of Cholesterol esterase in lactic acid bacteria

Abstract

Cholesterol esterase was purified from the broth filtration of 3 species including Lactobacillus acidophilus, Lactococcus lactic and Streptococcus thermophilus by precipitation with ammonium sulfate. The supernatant having purified enzyme was detected the cholesterol activity by titration with 1M NaOH and by thin layer chromatography. The detection was based on the determination the free fatty acid which is the product of cholesterol ester hydrolyzation of cholesterol esterase. The color change in titration and the spot appearance compared with the standard in TLC showed the presence of cholesterol esterase. The determination of cholesterol esterase was also performed with SDS poly-acrylamide gel electrophoresis to estimate the purified product.