Recombinant expression, characterization and application of maltotetraohydrolase from Pseudomonas saccharophila

Maltotetraohydrolase, widely used in food and medical fields, possesses the ability to hydrolyze starch to produce maltooligosaccharides with maltotetraose as the main product. It also has the potential usage in delaying bread aging.

Pseudomonas saccharophila maltotetraohydrolase was expressed in Bacillus subtilis WS11. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed obvious bands at 57 kDa (maltotetraohydrolase I) and 47 kDa (maltotetraohydrolase II). Both showed similar enzymatic properties, although the catalytic efficiency of maltotetraohydrolase I was 4.93 fold higher than that of maltotetraohydrolase II using soluble starch as substrate. In addition, the maltotetraohydrolase production was further scaled up in a 3-L fermentor, and the highest activity reached 1907 U mL^-1 . Then, the recombinant maltotetraohydrolase was used to produce maltotetraose. The maltotetraose yields catalyzed by maltotetraohydrolase I and II reached 73.2% and 69.7%, respectively. Finally, when recombinant maltotetraohydrolase was used in bread-making, texture profile analysis of the bread indicated recombinant maltotetraohydrolase I exhibited a significant anti-aging effect.

This is the first describing high-efficient expression of P. saccharophila maltotetraohydrolase in the food safety strain B. subtilis, and the yield represented the highest level ever reported. Excellent results were also obtained with respect to the preparation of maltotetraose and delaying bread aging using the recombinant maltotetraohydrolase. The present study will help lay the foundation for the industrial production and application of maltotetraohydrolase. © 2020 Society of Chemical Industry.