Effect of amino acids on free exopolysaccharide biosynthesis by Streptococcus thermophilus 937 in chemically defined medium
ABSTRACT: Free exopolysaccharide (f-EPS) produced by Streptococcus thermophilus improves the texture and functionality of fermented dairy foods. Our previous study showed a major improvement in f-EPS production of Strep. thermophilus 937 by increasing the concentrations of histidine, isoleucine, and...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2022-08-01
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| Series: | Journal of Dairy Science |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S002203022200340X |
| _version_ | 1828451861679570944 |
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| author | Yunchao Wa Chenchen Zhang Gulin Sun Hengxian Qu Dawei Chen Yujun Huang Ruixia Gu |
| author_facet | Yunchao Wa Chenchen Zhang Gulin Sun Hengxian Qu Dawei Chen Yujun Huang Ruixia Gu |
| author_sort | Yunchao Wa |
| collection | DOAJ |
| description | ABSTRACT: Free exopolysaccharide (f-EPS) produced by Streptococcus thermophilus improves the texture and functionality of fermented dairy foods. Our previous study showed a major improvement in f-EPS production of Strep. thermophilus 937 by increasing the concentrations of histidine, isoleucine, and glutamate to 15 mM in an optimized chemically defined medium. The aim of this study was to elucidate the effect of His, Ile, and Glu on the growth, f-EPS biosynthesis pathway, and carbohydrate metabolism profiles of Strep. thermophilus 937. The growth kinetics; transcript levels of key genes in the EPS biosynthesis pathway; enzyme activity involved in sugar nucleotide synthesis; concentrations of lactic acid, lactose, and galactose; and extracellular and intracellular pH were analyzed in chemically defined media with different initial histidine, isoleucine, and glutamate concentrations. The results showed that f-EPS production and viable cell counts of Strep. thermophilus 937 increased 2-fold after the concentrations of His, Ile, and Glu were increased. Additionally, increasing the concentrations of His, Ile, and Glu upregulated transcription of EPS biosynthesis genes and increased the activity of key enzymes in sugar nucleotide synthesis. Moreover, the consumption of lactose increased and secretion of galactose decreased, indicating that increasing the concentration of His, Ile, and Glu could enhance f-EPS production by maintaining viable cell counts, promoting sugar nucleotide synthesis, and increasing the transcript levels of the eps gene cluster. Our results provide a better understanding of the effect of AA on EPS biosynthesis in Strep. thermophilus. |
| first_indexed | 2024-12-10T23:43:53Z |
| format | Article |
| id | doaj.art-1391007e67ba44628e72242fbbbed122 |
| institution | Directory Open Access Journal |
| issn | 0022-0302 |
| language | English |
| last_indexed | 2024-12-10T23:43:53Z |
| publishDate | 2022-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Dairy Science |
| spelling | doaj.art-1391007e67ba44628e72242fbbbed1222022-12-22T01:28:58ZengElsevierJournal of Dairy Science0022-03022022-08-01105864606468Effect of amino acids on free exopolysaccharide biosynthesis by Streptococcus thermophilus 937 in chemically defined mediumYunchao Wa0Chenchen Zhang1Gulin Sun2Hengxian Qu3Dawei Chen4Yujun Huang5Ruixia Gu6Key Laboratory of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou 225127, Jiangsu Province, China; College of Animal Science and Technology, Yangzhou University, Yangzhou 225127, Jiangsu Province, ChinaKey Laboratory of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou 225127, Jiangsu Province, China; College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, ChinaKey Laboratory of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou 225127, Jiangsu Province, China; College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, ChinaKey Laboratory of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou 225127, Jiangsu Province, China; College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, ChinaKey Laboratory of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou 225127, Jiangsu Province, China; College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, ChinaKey Laboratory of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou 225127, Jiangsu Province, China; College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, ChinaKey Laboratory of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou 225127, Jiangsu Province, China; College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu Province, China; Corresponding authorABSTRACT: Free exopolysaccharide (f-EPS) produced by Streptococcus thermophilus improves the texture and functionality of fermented dairy foods. Our previous study showed a major improvement in f-EPS production of Strep. thermophilus 937 by increasing the concentrations of histidine, isoleucine, and glutamate to 15 mM in an optimized chemically defined medium. The aim of this study was to elucidate the effect of His, Ile, and Glu on the growth, f-EPS biosynthesis pathway, and carbohydrate metabolism profiles of Strep. thermophilus 937. The growth kinetics; transcript levels of key genes in the EPS biosynthesis pathway; enzyme activity involved in sugar nucleotide synthesis; concentrations of lactic acid, lactose, and galactose; and extracellular and intracellular pH were analyzed in chemically defined media with different initial histidine, isoleucine, and glutamate concentrations. The results showed that f-EPS production and viable cell counts of Strep. thermophilus 937 increased 2-fold after the concentrations of His, Ile, and Glu were increased. Additionally, increasing the concentrations of His, Ile, and Glu upregulated transcription of EPS biosynthesis genes and increased the activity of key enzymes in sugar nucleotide synthesis. Moreover, the consumption of lactose increased and secretion of galactose decreased, indicating that increasing the concentration of His, Ile, and Glu could enhance f-EPS production by maintaining viable cell counts, promoting sugar nucleotide synthesis, and increasing the transcript levels of the eps gene cluster. Our results provide a better understanding of the effect of AA on EPS biosynthesis in Strep. thermophilus.http://www.sciencedirect.com/science/article/pii/S002203022200340XStreptococcus thermophilusexopolysaccharideamino acidsregulation |
| spellingShingle | Yunchao Wa Chenchen Zhang Gulin Sun Hengxian Qu Dawei Chen Yujun Huang Ruixia Gu Effect of amino acids on free exopolysaccharide biosynthesis by Streptococcus thermophilus 937 in chemically defined medium Journal of Dairy Science Streptococcus thermophilus exopolysaccharide amino acids regulation |
| title | Effect of amino acids on free exopolysaccharide biosynthesis by Streptococcus thermophilus 937 in chemically defined medium |
| title_full | Effect of amino acids on free exopolysaccharide biosynthesis by Streptococcus thermophilus 937 in chemically defined medium |
| title_fullStr | Effect of amino acids on free exopolysaccharide biosynthesis by Streptococcus thermophilus 937 in chemically defined medium |
| title_full_unstemmed | Effect of amino acids on free exopolysaccharide biosynthesis by Streptococcus thermophilus 937 in chemically defined medium |
| title_short | Effect of amino acids on free exopolysaccharide biosynthesis by Streptococcus thermophilus 937 in chemically defined medium |
| title_sort | effect of amino acids on free exopolysaccharide biosynthesis by streptococcus thermophilus 937 in chemically defined medium |
| topic | Streptococcus thermophilus exopolysaccharide amino acids regulation |
| url | http://www.sciencedirect.com/science/article/pii/S002203022200340X |
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