Isomalto-Oligosaccharides Produced by Endodextranase Shewanella sp. GZ-7 From Sugarcane Plants

Abstract

Oligosaccharides have important alimental and medical applications. Dextranase has been used to produce isomalto-oligosaccharides (IMOs). In this study, we isolated dextranase-producing bacteria from sugarcane-cultivated soil. Identification of the isolate based on its phenotypical, physiological, and biochemical characteristics, as well as 16S ribosomal deoxyribonucleic acid gene sequencing yielded Shewanella sp. strain GZ-7. The molecular weight of the dextranase produced by this strain was 100-135 kDa. The optimum temperature and pH for dextranase production were 40 °C and 7.5, respectively. The enzyme was found to be stable at the pH range of 6.0-8.0 and the temperature range of 20 °C-40 °C. Thin-layer chromatography and high-performance liquid chromatography of the enzymolysis products of the substrate confirmed the enzyme to be endodextranase. Under the optimal conditions, the ratio of IMOs could reach 91.8% of the hydrolyzate. The final products were found to efficiently scavenge the 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, and superoxide anion radicals. In general, dextranase and hydrolyzates have high potential prospects for application in the future.