COMPARISON OF AMYLOLYTIC PROPERTIES OF LACTOBACILLUS-AMYLOVORUS AND OF LACTOBACILLUS-AMYLOPHILUS

Partially purified amylases produced by Lactobacillus amylovorus and L . amylophilus were compared and they differed in several properties. T he maximum amylase activity of L. amylovorus was higher than that of L . amylophilus. As estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, the molecular mass of the enzymes was 140 kDa for L. amylovorus amylase and 100 kDa for L. amylophilus amylase. Maximum enzymatic activities were obtained when the strains were grown in the presence of CaCO3, on maltose with L. amylovorus and on sucrose with L. amylophilus. Optimal activities were obtained at pH values between 5.0 and 6.0 for both amylases. The L. amylovorus amylase was stable at a higher temperature (50 degrees C) than the L. amylophilus amylase ( 40 degrees C). Of six substrates examined, greatest activity was obtai ned by both enzymes on soluble starch. Neither enzymes hydrolysed pull ulan or alpha- and beta-cyclodextrins. With the exception of Hg2+, whi ch partially inhibited both enzymes, various metal ions, such as 1 mM Ca2+ and Ba2+, stimulated L. amylophilus amylase activity whereas they inhibited L. amylovorus amylase activity.