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Automated Modular High Throughput Exopolysaccharide Screening Platform Coupled with Highly Sensitive Carbohydrate Fingerprint Analysis
Published on: April 11, 2016
Regulation of monosaccharide composition of anti-oxidant exopolysaccharide produced by Streptococcus salivarius
Yang Zhou1, Yanhua Cui1, Xiaojun Qu2
1Department of Food Nutrition and Health, School of Medicine and Health, Harbin Institute of Technology, Harbin, China.
Background:
Exopolysaccharides (EPSs) produced by Streptococcus salivarius subsp. thermophilus (SST) are characterized by anti-oxidant activities, and their monosaccharide composition correlates well with the expression of glycosyltransferase 2 family gene (gt25), UDP-glucose 4-epimerase gene (galE) and mannose-6 phosphate isomerase gene (manA). However, the relationship between anti-oxidant activity and monosaccharide composition of EPSs and the regulation of monosaccharide composition remains unclear.
Results:
This study took SST-CS6 as a research subject and constructed an over-expressed vector (pMG36C-p-groEL-gfp) for SST-CS6. In this recombination vector, the endogenous promoter of groEL induced the highest expressive level of green fluorescence gene expression compared to other 16 endogenous promoters. Under the effect of p-groEL, gt25, galE and manA have been over-expressed in SST-CS6, resulting in 49.2%, 54.5% and 22.1% increases in activity of Gt25, GalE and ManA, respectively. Additionally, overexpression of gt25, galE or manA influenced the production of crude EPS, ratio of acid EPS and monosaccharide composition of purified EPS. Overexpression of gt25 caused a 10.5% increase in the molar ratio of arabinose in acid EPS. Overexpression of galE significantly influenced the molar ratio of glucose and galactose in both neutral and acid EPS.
Conclusion:
A high molar ratio of arabinose contributed to high anti-oxidant activities of acid EPS. This study provides new insights for the biosynthesis of EPS with high anti-oxidant activities by overexpressing gt25 and galE in SST-CS6. © 2025 Society of Chemical Industry.
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