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A novel cold-adapted amylase-producing bacterium was isolated from seawater collected from Gaogong island of Jiangsu Province, China. The isolate was identified based on its phenotypes, biochemical test, and 16 S rRNA gene sequence as Pseudoalteromonas arctica and named GS230. The optimal activity temperature of isolate GS230 amylase was 30°C, and the activity decreased dramatically at temperatures above 40°C. Compared with the amylase from mesophiles and thermophiles, the cold-adapted amylase showed higher enzyme activity at low temperature and a greater degree of heat sensitivity at temperatures higher than 40°C. Ca2+ showed a significant effect on maintaining the activity of the enzyme. The α-amylase could have important applications in the food industry. A number of factors affecting the production of the extracellular amylase were investigated. Soluble starch and beef extract were the most promising carbon and nitrogen sources, respectively. When the strain was cultured at 20°C, pH 8.0 for 24 h, the amylase activity peaked at 780.4 U/ml.

A cold-adapted α-amylase (ParAmy) gene from Pseudoalteromonas arctica GS230 was cloned, sequenced, and expressed as an N-terminus His-tag fusion protein in E. coli. A recombinant protein was produced and purified with DEAE-sepherose ion exchange chromatography and Ni affinity chromatography. The molecular weight of ParAmy was estimated to be 55 KDa with sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE). With an optimum temperature for activity 30 °C, ParAmy showed 34.5% of maximum activity at 0 °C and its activity decreased sharply at above 40 °C. ParAmy was stable in the range of pH 7–8.5 at 30 °C for 1 h. ParAmy was activated by Mn2+, K+ and Na+, and inhibited by Hg2+, Cu2+, and Fe3+. N-Bromosuccinimid showed a significant repressive effect on enzyme activity. The K m and V max values of the α-amylase for soluble starch were 7.28 mg/mL and 13.07 mg/mL min, respectively. This research suggests that Paramy has a good potential to be a cold-stable and alkalitolerant amylase in detergent industry.