Isolation and purification of starch hydrolysing amylase from Streptomyces sp. Al-Dhabi-46 obtained from the Jazan region of Saudi Arabia with industrial applications

Amylase is an important industrially useful enzyme with various applications, widely explored for their applications in food and biofuel industries. In this study, seventeen actinomycetes strains were isolated from the soil sample and screened for amylase biosynthesis. Among the 17 isolates, nine actinomycetes showed activity on starch agar plates. The strain Al-Dhabi-46 showed more hydrolytic zone (19 mm) on starch agar plates. It was identified by biochemical characters and 18S rDNA sequencing and characterized as Streptomyces sp. Al-Dhabi-46. Amylase production was found to be maximum after 5 days of incubation (108 +/- 4.1 U/ml) and at pH 8.0 (118.1 +/- 2.3 U/ml) and at 40 degrees C (124 +/- 12.1 U/ml). Amylase synthesis was high in the medium containing starch (208 +/- 11.4 U/ml). Amylase production was 241 +/- 18.1 U/ml in the culture medium supplemented with beef extract and 0.1% Mn2+ ions significantly enhanced amylase production. The molecular weight of purified amylase from Streptomyces sp. Al-Dhabi-46 was 44 kDa. Amylase was highly active up to pH 8.0 and at 40 degrees C. Amylase activity was enhanced by the addition of Mn2+ at 10 mM concentrations. Purified amylase from Streptomyces sp. Al-Dhabi-46 digested cassava starch at 25% and 55%, 78% and 95.4% level after 15 min, 30 min, 45 min and 60 min of enzymatic reaction. Enhanced production of amylase enzyme from the Streptomyces sp. Al-Dhabi-46 attract for the production of industrially important products. (C) 2019 The Authors. Published by Elsevier B.V. on behalf of King Saud University.