Characterization of an exopolysaccharide (EPS-3A) produced by Streptococcus thermophilus ZJUIDS-2-01 isolated from traditional yak yogurt.

Autor: Cao F; Institute of Dairy Science, College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China., Liang M; Institute of Dairy Science, College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China., Liu J; Institute of Dairy Science, College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China., Liu Y; College of Life Science, Zhejiang University, Hangzhou 310058, PR China., Renye JA Jr; Dairy and Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA., Qi PX; Dairy and Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA. Electronic address: Phoebe.Qi@usda.gov., Ren D; Institute of Dairy Science, College of Animal Sciences, Zhejiang University, Hangzhou 310058, PR China. Electronic address: dxren@zju.edu.cn.
Jazyk: angličtina
Zdroj: International journal of biological macromolecules [Int J Biol Macromol] 2021 Dec 01; Vol. 192, pp. 1331-1343. Date of Electronic Publication: 2021 Oct 19.
DOI: 10.1016/j.ijbiomac.2021.10.055
Abstrakt: Yak yogurt, one of the naturally fermented dairy products prepared by local herdsmen in the Qinghai-Tibet Plateau, contains a diverse array of microorganisms. We isolated and identified a novel Streptococcus thermophilus strain, ZJUIDS-2-01, from the traditional yak yogurt. We further purified and carried out detailed structural, physiochemical, and bioactivity studies of an exopolysaccharide (EPS-3A) produced by S. thermophilus ZJUIDS-2-01. The weight-average molecular weight (Mw) of EPS-3A was estimated to be 1.38 × 10 6  Da by High-Performance Gel Permeation Chromatography (HPGPC). The monosaccharide analysis established its composition to be glucose, galactose, N-acetyl-D-galactosamine, and rhamnose in a ratio of 5.2:2.5:6.4:1.0. The molecular structure of EPS-3A was determined by the combination of permethylation analysis, FT-IR, and NMR spectroscopic techniques. The ζ-potential measurements indicated that EPS-3A had a pKa value of ~4.40. The DSC yielded a melting point (T m ) of 80.4 °C and enthalpy change (ΔH) of 578 J/g for EPS-3A, comparable to those of the xanthan gum (XG), a commercial EPS. EPS-3A exhibited better O/W emulsion stability and flocculating capacity than XG. Furthermore, it also demonstrated similar antioxidant activity to XG and promising in vitro antibacterial properties. This work evidenced that EPS-3A derived from S. thermophilus ZJUIDS-2-01 holds the potential for food and industrial applications.
(Published by Elsevier B.V.)
Databáze: MEDLINE
Externí odkaz: