Characterization of a novel type I L-asparaginase from Acinetobacter soli and its ability to inhibit acrylamide formation in potato chips

L-Asparaginases have the potential to inhibit the formation of acrylamide, a harmful toxin formed during high temperature processing of food. A novel bacterium which produces L-asparaginase was screened. Type I L-asparaginase gene from Acinetobacter soli was cloned and expressed in Escherichia coli. The recombinant L-asparaginase had an activity of 42.0 IU mL⁻¹ and showed no activity toward L-glutamine and D-asparagine. The recombinant L-asparaginase exhibited maximum catalytic activity at pH 8.0 and 40°C. The enzyme was stable in the pH ranging from 6.0 to 9.0. The activity of the recombinant enzyme was substantially enhanced by Ba²⁺, dithiothreitol, and β-mercaptoethanol. The K_m and V_max values of the L-asparaginase for the L-asparagine were 3.22 mmol L⁻¹ and 1.55 IU μg⁻¹, respectively. Moreover, the recombinant L-asparaginase had the ability to mitigate acrylamide formation in potato chips. Compared with the untreated group, the content of acrylamide in samples treated with the enzyme was effectively decreased by 55.9%. These results indicate that the novel type I L-asparaginase has the potential for application in the food processing industry.