Vasanthy Arasaratnam and Kulasingam Thayaananthan
This study was aimed at improving a- amylase production by Bacillus RB4. Bacillus RB4 isolated from rice broth was grown in a medium containing (gL-1) starch, 2.0; CaCl2.2H2O, 0.01; MgCl2.6H2O, 0.01; FeCl2, 0.01; K2HPO4, 2.5; KH2PO4, 10.0; peptone, 4.0; NaCl, 2.0 and (NH4)2SO4, 4.0. Decrease in the phosphate ion concentration in the fermentation medium decreased the enzyme production. Sodium dodecyl sulphate (0.05% w/v) and succinic acid (0.1 and 0.5gL-1) reduced a-amylase production while Tween 80 (0.1, 1.0 and 5.0% v/v) did not improve a-amylase production. Soluble starch (4.5gL-1) increased the enzyme production by 1.5 times. Two-fold increase in the enzyme production was observed with sesame oil (18mLL-1) supplementation in addition to 4.5gL-1 soluble starch while coconut oil (3.0mLL1) completely stopped a-amylase production. Thus by optimizing the medium 4.26 fold increase in a-amylase production by Bacillus RB4 was achieved.
