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

• Published in: International journal of biological macromolecules 2021-01, Vol.166, p.61-70
• Main Authors: Gao, Hongliang, Yang, Li, Tian, Jiangtao, Huang, Lingling, Huang, Dating, Zhang, Wei, Xie, Fangrui, Niu, Yanning, Jin, Mingfei, Jia, Caifeng, Zou, Chunjing, Huang, Jing, Chang, Zhongyi, Yang, Xuexia, Jiang, Deming
• Format: Article
• Language: English
• Subjects: Agrobacterium tumefaciens - genetics; Agrobacterium tumefaciens - metabolism; Carbohydrate Conformation; Elastic Modulus; Hot Temperature; Mutation; Polysaccharides, Bacterial - biosynthesis; Polysaccharides, Bacterial - chemistry; Rheological properties; Rheology; Rhizobium radiobacter; Succinoglycan; Viscosity
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2020.10.087

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 1.55 × 107 Da and 1.26 × 106 Da, respectively. While, succinoglycan SG-N from the mutant strain was a homogeneous polysaccharide, and the molecular weight was 1.01 × 107 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 °C, indicating the thermally induced order-disorder conformation. The results of effect of concentrations (2.5–15%) and temperatures (25–75 °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.