Characterization and rheological properties analysis of the succinoglycan produced by a high-yield mutant of Rhizobium radiobacter ATCC 19358

Succinoglycan is an industrially important exopolysaccharide biosynthesized by bacteria. In this study, mutant strain 18052 N-11 was obtained from the wild type strain Rhizobium radiobacter ATCC 19358 by NTG mutagenesis. It has a high yield succinoglycan of 32.5 g/l cultured in a 15 L-fementer for 72 h. Succinoglycan SG-A from the wild type strain has two components, and the molecular weights were 155 x 10(7) Da and 1.26 x 10(6) Da, respectively. While, succinoglycan SG-N from the mutant strain was a homogeneous polysaccharide, and the molecular weight was 1.01 x 10(7) Da. The molecular weight of both succinoglycan was higher than those reported in literatures. DSC thermogram of SG-A showed a higher endothermic peak than that of SG-N due to the higher crystallinity of SG-A. The dynamic frequency sweep test of SG-A and SG-N showed that the elastic modulus G' and viscosity modulus G '' curves intersected at 65 degrees C, indicating the thermally induced order-disorder conformation. The results of effect of concentrations (2.5-15%) and temperatures (25-75 degrees C) on apparent viscosity of SG-A and SG-N showed that the succinoglycan solutions exhibited non-Newtonian, shear-thinning behavior. Both SG-A and SG-N showed an excellent emulsification activity. The characterizations and rheological properties make SG-A and SG-N prominent candidates in food, cosmetics, pharmaceutical and petroleum industries. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Succinoglycan is an important exopolysaccharide biosynthesized by bacteria. A mutant strain N-11 showed a high yield, with wild type strain having two components and mutant strain having a homogeneous polysaccharide. SG-A exhibited higher crystallinity than SG-N, and both showed non-Newtonian, shear-thinning behavior in response to concentrations and temperatures. Both SG-A and SG-N displayed excellent emulsification activity, making them promising candidates in various industries.