ACID-STABLE AND THERMOSTABLE ALPHA-AMYLASE FROM BACILLUS-LICHENIFORMIS-ALPHA

Bacillus licheniformis alpha which was recently isolated from soil pro duces a novel acid-stable and thermostable alpha-amylase. The optimum pH and optimum temperature of the amylase were 4.5-5.3 and around 90-d egrees-C, respectively. In the presence of Ca2+, the optimum temperatu re was observed at around 100-degrees-C. Under conditions in which a s tarch slurry (pH 4.5) was incubated with the amylase for 5 min at 105- degrees-C (the primary liquefaction) and further incubation of the pri mary liquefied starch for 0.5-6 h at 90-degrees-C to promote dextriniz ation with the remaining amylase activity (secondary liquefaction) was carried out, liquefied starch having pH and DE values which are suita ble for saccharification with glucoamylase from Aspergillus niger, was obtained.