Physicochemical characteristics and bioactivities of the exopolysaccharide and its sulphated polymer from Streptococcus thermophilus GST-6.
Exopolysaccharide (EPS) produced by Streptococcus thermophilus GST-6 in skim milk was extracted and purified. The EPS was composed of glucose and galactose in a molar ratio of 1.80:1.03 with identical primary structure to the EPS from S. thermophilus ST1 reported previously. The purified EPS was sulphated at a sulphonation degree of 0.26±0.03, and presence of sulphate groups in the sulphated EPS (SEPS) was confirmed. Microstructural studies demonstrated a porous web with coarse surface for the EPS while the SEPS appeared as stacked flakes with relatively uniform shapes. Sulphonation of the EPS slightly decreased its degrading temperature from 234.6°C to 232.5°C. The DPPH, superoxide and hydroxyl radicals scavenging activities of the EPS were significantly (P<0.05) improved after sulphonation. The SEPS also showed stronger inhibitory activity than the EPS against Eschericia coli, Salmonella typhimurium and Staphylococcus aureus.
Beijing Laboratory of Food Quality and Safety, Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China. Electronic address: jian_zh@outlook.com.
Jian
J
Zhang
Beijing Laboratory of Food Quality and Safety, Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China. Electronic address: 1028415414@qq.com.
Yongqiang
Y
Cao
College of Food Science and Engineering, Jilin Agricultural University, Changchun, China. Electronic address: 282047573@qq.com.
Ji
J
Wang
Beijing Laboratory of Food Quality and Safety, Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China. Electronic address: 610850207@qq.com.
Xialei
X
Guo
Beijing Laboratory of Food Quality and Safety, Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China. Electronic address: 495826322@qq.com.
Yi
Y
Zheng
Beijing Laboratory of Food Quality and Safety, Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China. Electronic address: 1203782898@qq.com.
Wen
W
Zhao
Beijing Laboratory of Food Quality and Safety, Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China. Electronic address: 738618825@qq.com.
Xueyang
X
Mei
Beijing Laboratory of Food Quality and Safety, Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China. Electronic address: 1605595746@qq.com.
Ting
T
Guo
Beijing Laboratory of Food Quality and Safety, Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University, Beijing, China. Electronic address: yangzhennai@th.btbu.edu.cn.
Zhennai
Z
Yang
D001704:Biopolymers / Q000737:chemistry* / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects; D011134:Polysaccharides / Q000737:chemistry* / Q000494:pharmacology; D012486:Salmonella typhimurium / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects; D048249:Streptococcus thermophilus / Q000378:metabolism*
D001704:Biopolymers; D011134:Polysaccharides
Antibacterial activity; Antioxidant; Arabinose (PubChem CID: 66308); Ascorbic acid (PubChem CID: 72941984); D-Glucose (PubChem CID: 5793); Exopolysaccharide; Galactose (PubChem CID: 6036); Penicillin G (PubChem CID: 5904); Rhamnose (PubChem CID: 25310); Streptococcus thermophilus GST-6; Sulphonation; Sulphur trioxide pyridine complex (PubChem CID: 168533); Xylose (PubChem CID: 135191)