Heterologous Expression of Trehalose Synthase from a Thermophilic Actinomyces in Bacillus licheniformis

Abstract:

Trehalose synthase could transform maltose to trehalose via isomerization, which is a crucial enzyme in the process of trehalose biotransformation with enzymatic method. Recombinant expression plasmid was constructed in order to effectively produce food-grade trehalose synthase in food safety host. The plasmid harbored a trehalose synthase encoding gene from Thermomonosporacurvata, which was expressed under the control of a xylose operon from Bacillus megaterium. The enzyme activity yield of intracellular trehalose synthase reached to 12.1 U/mL after fermentation when expressed by xylose isomerase promoter and its repressor protein in Bacillus licheniformis. Furthermore, the effect of different cultural conditions on the enzyme production was investigated and the optimal condition was determined with 4% maltodextrin, 0.4% soybean powder, and 1% inducer added after 10 h incubation. The maximal yield was 23.7 U/mL after 12 h induction at 37 ℃.The study would contribute to the industrial application of trehalose synthase from both theoretical and experimental aspects.