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Thermostable α-amylase from moderately halophilic Halomonas sp. AAD21

The 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. | K. S. UZYOL, B. SARIYAR AKBULUT, A. A. DENİZCİ, D. KAZAN Turk J Biol 36 (2012) 327-338 © TÜBİTAK doi:10.3906/biy-1106-7 Thermostable α-amylase from moderately halophilic Halomonas sp. AAD21 Kamil Serkan UZYOL1, Berna SARIYAR AKBULUT2, Aziz Akın DENİZCİ3, Dilek KAZAN2 1 Institute for Graduate Studies in Pure and Applied Science, Marmara University, Göztepe Campus, 34722 Kadıköy, İstanbul - TURKEY 2 Bioengineering Department, Engineering Faculty, Marmara University, Göztepe Campus, 34722 Kadıköy, İstanbul - TURKEY 3 The Scientific and Technological Research Council of Turkey (TÜBİTAK), Genetic Engineering and Biotechnology Institute, Marmara Research Center, Gebze, Kocaeli - TURKEY Received: 06.06.2011 Abstract: The 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. The 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. This 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. The optimum pH and temperature of the α-amylase were found to be 7.0 and 50 °C, respectively. The α-amylase synthesized by Halomonas sp. AAD21 was also thermostable. Crude α-amylase did not lose its original activity after 2 h of incubation at 50 °C and 60 °C, and it retained 70% of its original activity after 120 min of incubation at 90 °C. Key words: Moderate .