Production of Thermostable and Acidophilic Amylase from Thermophilic Bacillus licheniformis JAR-26

Abstract

The present study has been conducted on 120 bacterial isolates collected from spoiled starchy materials like wheat flour and bread dough, soil and spoiled sour materials like tomatoes, citrus fruits and pears etc. These isolates were screened for the production of extracellular acidophilic and thermostable amylases. Five isolates exhibited good amylase activity. Preliminary identification of these isolates showed that they all belong to the genus Bacillus, so they were designated as Bacillus sp. JAR-4, JAR-26, JAR-29, JAR-53 and JAR-76. Isolate JAR-26 showing maximum starch hydrolysis was further subjected to biochemical testing and on the basis of results it was designated as Bacillus licheniformis JAR-26. It was able to grow up to 55 0C at pH 5.5 and showed remarkable liquefaction as well as saccharification activity. The optimum period for maximum cell growth and amylase production in case of Bacillus sp. JAR-26 was found to be 36 h at 45 0C. The optimum temperature for enzyme assay was 85 0C at pH 5.5. The enzyme was also thermostable as 100% activity was observed at 85 0C and 55% activity retained at 100 0C and 48% activity at 104 0C when heated for 30 min.