Potential antimicrobial and fruit juice clarification activity of amylase enzyme from Bacillus strains

Abstract

The hydrolytic enzyme, amylase possesses wide industrial applications and its production from bacterial sources by submerged fermentation is much simplified and economical. The research aimed to characterize amylase-producing bacteria and evaluate their potential for amylase activity regarding antimicrobial and fruit juice clarification. In current study, Bacillus licheniformis, Bacillus amyloliquifaciens, Bacillus cereus, Bacillus subtilis and Bacillus paramycoides was identified by 16S rRNA sequencing. After submerged fermentation, amylase activity of bacteria was measured by 3, 5-dinitro salicylic acid (DNS) assay. A substantial amount of amylase (423.47 mg/ml) in crude extract was measured by Bradford protein assay. Later, ammonium sulfate (80 %) precipitated partially purified amylase showed 1.6 times enhanced amylase activity (1484.94 U/ml) compared to crude amylase (973.23 U/ml). For highest amylase production, 72 h of optimum fermentation period was recorded at pH 7 with 2 % starch as substrate. Potent thermophilic amylase activity was observed at 65 °C. In apple juice clarification activity of amylase, turbidity of juice was reduced to 54.18 %. Potential antimicrobial property of amylase was detected with largest zone of inhibition against Escherichia coli ATCC 25922 (22.36 mm) and Mucor sp. ATCC 48559 (22.45 mm). Considering promising amylase properties, amylase-producing Bacillus strains from rice mill soil can be fermented for large scale amylase production providing application for industrial purposes including fruit juice clarification and antimicrobial activities. It will also overthrow the requirement of employing expensive and harmful chemicals in fruit juice clarification and combating pathogens.