Th ermostable α-amylase from moderately halophilic

Abstract: Th e moderately halophilic Halomonas sp. strain AAD21, which produces extracellular thermostable α-amylase, was isolated from the Çamaltı Saltern area located in İzmir, Turkey. NaCl, carbon, and nitrogen sources in the growth medium were optimized to enhance α-amylase yield. Th e highest enzyme yield was measured in the presence of 20% NaCl with peptone as the nitrogen and starch as the carbon sources in the fermentation broth. Th is microorganism was also found to utilize waste potato peel as a carbon source for α-amylase production. Concentrations of carbon and nitrogen sources were optimized using a statistical approach, and α-amylase activity increased from 4.07 U mL–1 min–1 to 26.25 U mL–1 min–1. Maximum α-amylase production was achieved at the end of 48 h of growth in the presence of 20 % NaCl, 4.12 % starch, 1.0 % peptone, 0.2 % KCl, 2 % MgSO4·7H2O, and 0.03 % trisodium citrate pentahydrate. Th e optimum pH and temperature of the α-amylase were found to be 7.0 and 50 °C, respectively. Th e α-amylase synthesized by Halomonas sp. AAD21 was also thermostable. Crude α-amylase did not lose its original activity aft er 2 h of incubation at 50 °C and 60 °C, and it retained 70 % of its original activity aft er 120 min of incubation at 90 °C