Structural characterisation of EPS of Streptococcus thermophilus S-3 and its application in milk fermentation

Zhiyuan Xu; Qingbin Guo; Hui Zhang; Zhiqiang Xiong; Xiumin Zhang; Lianzhong Ai

doi:10.1016/j.ijbiomac.2021.02.173

Structural characterisation of EPS of Streptococcus thermophilus S-3 and its application in milk fermentation

Int J Biol Macromol. 2021 May 1:178:263-269. doi: 10.1016/j.ijbiomac.2021.02.173. Epub 2021 Feb 24.

Authors

Zhiyuan Xu¹, Qingbin Guo², Hui Zhang³, Zhiqiang Xiong³, Xiumin Zhang², Lianzhong Ai⁴

Affiliations

¹ Shanghai Engineering Research Center of Food Microbiology, School of Medical Instruments and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China; State Key Laboratory of Dairy Biotechnology, Technology Center Bright Dairy & Food Co., Ltd, Shanghai 200436, China.
² State Key Laboratory of Food Nutrition and Safety, College of Food Science and Technology, Tianjin University of Science and Technology, Tianjin 300457, China.
³ Shanghai Engineering Research Center of Food Microbiology, School of Medical Instruments and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
⁴ Shanghai Engineering Research Center of Food Microbiology, School of Medical Instruments and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China. Electronic address: ailianzhong@163.com.

PMID: 33639187
DOI: 10.1016/j.ijbiomac.2021.02.173

Abstract

The application of Streptococcus thermophilus S-3 into yogurt production was studied and the structural properties of the generated exopolysaccharides (EPS-S3) were characterized. The proposed structure of EPS-S3 was obtained. EPS-S3 contained a high ratio of N-Acetyl-galactosamine with the Mw of 574 kDa, which was higher than that of AR333 (314 kD) leading to higher apparent viscosity. Streptococcus thermophilus strain S-3 was co-cultured with Lactobacillus delbrueckii for yogut production which highly increased the acidifying rate and post-acidification rate. The quality of the co-cultured yogurts in terms of apparent viscosity, syneresis capacity, water holding capacity and rheological properties were much better than that by using Lactobacillus bulgaricus only. The production mechanism of EPS-S3 from gene regulated level was also discussed which is helpful to facilitate the application of Streptococcus thermophilus strain into milk production.

Keywords: Co-culture; Exopolysaccharides; NMR; Streptococcus thermophilus.

MeSH terms

Cultured Milk Products / microbiology*
Lactobacillus delbrueckii / growth & development
Polysaccharides, Bacterial* / chemistry
Polysaccharides, Bacterial* / pharmacology
Streptococcus thermophilus / chemistry*

Substances

Polysaccharides, Bacterial