Production and Partial Characterization of <i>α</i> ‐Amylase Enzyme from Marine Actinomycetes

Abstract

Amylase producing actinobacteria were isolated and characterized from terrestrial environment. There are a limited number of reports investigating the marine environment; hence, in the present study, four marine enzymes were tested for their amylase production ability. On starch agar plates, the <i>Streptomyces rochei</i> strain showed a higher hydrolytic zone (24 mm) than the other isolates. Growth under optimized culture conditions using Plackett-Burman's experimental design led to a 1.7, 9.8, 7.7, and 3.12-fold increase for the isolates <i>S. griseorubens</i>, <i>S. rochei</i>, <i>S. parvus</i>, and <i>Streptomyces</i> sp., respectively, in the specific activity measurement. When applying the Box-Behnken design on <i>S. rochei</i> using the most significant parameters (starch, K₂HPO₄, pH, and temperature), there was a 12.22-fold increase in the specific activity measurement 7.37 U/mg. The <i>α</i>-amylase was partially purified, and its molecular weight was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. <i>α</i>-Amylase was particularly active at pH 6 and 65°C. The purified enzyme was most active at 65°C and pH 6, thermal stability of 70°C for 40 min, and salt concentration of 1 M with Km and Vmax of 6.58 mg/ml and 21.93 <i>μ</i>mol/ml/min, respectively. The <i>α</i>-amylase was improved by adding Cu⁺², Zn⁺², and Fe⁺² (152.21%, 207.24%, and 111.89%). Increased production of <i>α</i>-amylase enzyme by <i>S. rochei</i> KR108310 leads to production of significant industrial products.