A high-yield low-temperature amylase strain was screened from frozen Antarctic krill shrimp meat, and its enzymatic properties were studied to improve the thermal stability of the enzyme. According to the morphological characteristics, physiological and biochemical identification and 16S rRNA sequence alignment, the results showed that the strain were Pseudomonas lactis and were named Pseudomonas lactis A5-2. The enzymatic properties analysis indicated that the optimum reaction temperature of the enzyme was 20 ℃, and the optimum pH was 6.0, which was a typical weakly acidic low-temperature amylase. Fe3+, Cu2+ and Mn2+had different inhibiting effect on enzymes. K+, Mg2+, Ca2+and Na+ showed different activation on enzymes. Among them, Cu2+had the strongest inhibitory effect on enzymes, and Na+ had the strongest activation effect on enzymes. After adding Na+ and Ca2+ simultaneously in the reaction system, the half-life of the enzyme was extended from 20 min to 80 min, which was four times that of no metal ions, which effectively improved the thermal stability of the enzyme. The low-temperature amylase screened in this experiment could adapt to the low temperature environment well and improve the thermal stability of the enzyme, which provides a basis for the separation and purification of and industrial production and application enzyme.
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