Bacillus licheniformis BT5.9 Isolated from Changar Hot Spring, Malang, Indonesia, as a Potential Producer of Thermostable α-amylase

A total of 34 bacterial isolates were obtained from soil samples collected from Changar Hot Spring, Malang, Indonesia. Of these, 13 isolates produced a zone of hydrolysis in starch-nutrient agar medium and generated various amylases in liquid medium. One isolate was selected as the best amylase producer and was identified as Bacillus licheniformis BT5.9. The improvement of culture conditions (initial medium pH of 5.0, cultivation temperature of 50°C, agitation speed of 100 rpm and inoculum size of 1.7 × 10(9) cells/ml) provided the highest amylase production (0.327 U/ml).