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ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Food Microbiology
Volume 15 - 2024 |
doi: 10.3389/fmicb.2024.1476940
The transcriptional regulation effects of histidine, isoleucine and glutamate on free exopolysaccharide biosynthesis of Streptococcus thermophilus 937
Provisionally accepted
Yunchao Wa
1,2
Xia Zhao
1,3*
Zhang Chenchen
1,3
Hengxian Qu
1,3*
Dawei Chen
3,4
Xia Chen
3*
Yujun Huang
3,4*
Ruixia Gu
3,4*- 1 Yangzhou University, Other, Yangzhou, China
- 2 Yangzhou University, Key Lab of Dairy Biotechnology and Safety Control, Yangzhou, China
- 3 Key Lab of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou, Jiangsu Province, China
- 4 College of Food Science and Engineering ,Yangzhou university, Yangzhou, China
The free exopolysaccharide (f-EPS) produced by Streptococcus thermophilus is a natural texture modifier and has a variety of prebiotic activities. Our previous studies showed f-EPS production from S. thermophilus 937 was increased 2-fold in the presence of 15 mM of glutamate, isoleucine, and histidine in the chemically defined medium. In this study, we used transcriptomics and qPCR to further explore the specific mechanism of the enhanced effect of 3 amino acids on the f-EPS biosynthesis of S. thermophilus 937. The mRNA-seq analysis and targeted pathway analysis indicated that genes associated with histidine/valine/leucine/isoleucine/phenylalanine/tyrosine/tryptophan synthesis, galactose metabolism, purine metabolism and quorum sensing in S. thermophilus 937 were significantly upregulated under increasing concentrations of histidine, isoleucine and glutamate in chemically defined medium (CDM). qPCR results showed that the significant upregulation of galactose metabolism- and nucleotide sugar synthesis-related genes was attributed to the increase in glutamate concentration, and glutamate could induce the expression of galR. The upregulation of epsA, epsB, and epsD transcript levels was caused by the increase in histidine concentration. The upregulation of transcript levels of genes related to phenylalanine/ tyrosine/ tryptophan/ histidine/ valine/ leucine/ isoleucine synthesis was caused by the increase in isoleucine concentrations. This indicates that 3 amino acids have different mechanisms for enhancing the biosynthesis of f-EPS in S. thermophilus 937.
Keywords: Streptococcus thermophilus, Amino acid, Exopolysaccharide, Transcriptomics, quantitative PCR
Received: 06 Aug 2024; Accepted: 12 Dec 2024.
Copyright: © 2024 Wa, Zhao, Chenchen, Qu, Chen, Chen, Huang and Gu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Xia Zhao, Key Lab of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou, Jiangsu Province, China
Hengxian Qu, Key Lab of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou, Jiangsu Province, China
Xia Chen, Key Lab of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou, Jiangsu Province, China
Yujun Huang, Key Lab of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou, Jiangsu Province, China
Ruixia Gu, Key Lab of Dairy Biotechnology and Safety Control, Yangzhou University, Yangzhou, Jiangsu Province, China
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