Multi-omics analysis reveals the mechanism for galactose metabolism in mutant Streptococcus thermophilus IMAU20551Y

Streptococcus thermophilus (S. thermophilus) is a species widely used in the dairy industry to accelerate the acidification rate and improve the texture and flavour characteristics of dairy products. However, most S. thermophilus have galactose-negative (Gal−) phenotypes, which can lead to accumulat...

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Main Authors: Jiahui Tai, Haimin Hu, Jinhui Liu, Wenhui Lu, Tong Dan
Format: Article
Language:English
Published: Elsevier 2025-01-01
Series:Current Research in Food Science
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Online Access:http://www.sciencedirect.com/science/article/pii/S2665927125000486
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author Jiahui Tai
Haimin Hu
Jinhui Liu
Wenhui Lu
Tong Dan
author_facet Jiahui Tai
Haimin Hu
Jinhui Liu
Wenhui Lu
Tong Dan
author_sort Jiahui Tai
collection DOAJ
description Streptococcus thermophilus (S. thermophilus) is a species widely used in the dairy industry to accelerate the acidification rate and improve the texture and flavour characteristics of dairy products. However, most S. thermophilus have galactose-negative (Gal−) phenotypes, which can lead to accumulation of free galactose in fermented dairy products. In a previous study, a mutant of S. thermophilus IMAU20551Y was obtained by N-methyl-N′-nitro-N-nitrosoguanidine (NTG) mutagenesis in which key enzymes related to galactose metabolism were significantly changed compared with the wild type. β-galactosidase and galactokinase activity were higher in the mutant while glucokinase and pyruvate kinase activities were significantly decreased compared with the wild type. In this study, the ability of the mutant to metabolize galactose was verified by high performance liquid chromatography (HPLC), and the mechanism for enhanced galactose metabolism elucidated by multi-omics analysis. HPLC analysis showed that accumulation of galactose in milk fermented by mutant S. thermophilus IMAU20551Y was reduced by 41.4%, compared with the wild type. Although no mutations in gene sequences associated with galactose metabolism were detected by genome sequencing, transcriptomic data showed up-regulation in expression of galM, galK, galT, galE (associated with the Leloir pathway) and LacI family transcriptional regulator GalR, resulting in enhanced galactose metabolism in the mutant. This study provides a reference for genetic engineering modification of galactose-positive (Gal+) S. thermophilus, which is expected to be used as a starter for the production of low galactose fermented dairy products.
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spelling doaj-art-6ac113fcad8f40b199f3cf2c33ce756a2025-08-20T02:06:24ZengElsevierCurrent Research in Food Science2665-92712025-01-011010101710.1016/j.crfs.2025.101017Multi-omics analysis reveals the mechanism for galactose metabolism in mutant Streptococcus thermophilus IMAU20551YJiahui Tai0Haimin Hu1Jinhui Liu2Wenhui Lu3Tong Dan4Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, China; Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, China; Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, ChinaKey Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, China; Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, China; Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, ChinaKey Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, China; Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, China; Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, ChinaKey Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, China; Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, China; Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, ChinaKey Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, China; Key Laboratory of Dairy Products Processing, Ministry of Agriculture and Rural Affairs, Inner Mongolia Agricultural University, Hohhot, China; Inner Mongolia Key Laboratory of Dairy Biotechnology and Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China; Corresponding author. Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Hohhot, China.Streptococcus thermophilus (S. thermophilus) is a species widely used in the dairy industry to accelerate the acidification rate and improve the texture and flavour characteristics of dairy products. However, most S. thermophilus have galactose-negative (Gal−) phenotypes, which can lead to accumulation of free galactose in fermented dairy products. In a previous study, a mutant of S. thermophilus IMAU20551Y was obtained by N-methyl-N′-nitro-N-nitrosoguanidine (NTG) mutagenesis in which key enzymes related to galactose metabolism were significantly changed compared with the wild type. β-galactosidase and galactokinase activity were higher in the mutant while glucokinase and pyruvate kinase activities were significantly decreased compared with the wild type. In this study, the ability of the mutant to metabolize galactose was verified by high performance liquid chromatography (HPLC), and the mechanism for enhanced galactose metabolism elucidated by multi-omics analysis. HPLC analysis showed that accumulation of galactose in milk fermented by mutant S. thermophilus IMAU20551Y was reduced by 41.4%, compared with the wild type. Although no mutations in gene sequences associated with galactose metabolism were detected by genome sequencing, transcriptomic data showed up-regulation in expression of galM, galK, galT, galE (associated with the Leloir pathway) and LacI family transcriptional regulator GalR, resulting in enhanced galactose metabolism in the mutant. This study provides a reference for genetic engineering modification of galactose-positive (Gal+) S. thermophilus, which is expected to be used as a starter for the production of low galactose fermented dairy products.http://www.sciencedirect.com/science/article/pii/S2665927125000486Streptococcus thermophilusGalactose metabolismGenomic analysisTranscriptome analysis
spellingShingle Jiahui Tai
Haimin Hu
Jinhui Liu
Wenhui Lu
Tong Dan
Multi-omics analysis reveals the mechanism for galactose metabolism in mutant Streptococcus thermophilus IMAU20551Y
Current Research in Food Science
Streptococcus thermophilus
Galactose metabolism
Genomic analysis
Transcriptome analysis
title Multi-omics analysis reveals the mechanism for galactose metabolism in mutant Streptococcus thermophilus IMAU20551Y
title_full Multi-omics analysis reveals the mechanism for galactose metabolism in mutant Streptococcus thermophilus IMAU20551Y
title_fullStr Multi-omics analysis reveals the mechanism for galactose metabolism in mutant Streptococcus thermophilus IMAU20551Y
title_full_unstemmed Multi-omics analysis reveals the mechanism for galactose metabolism in mutant Streptococcus thermophilus IMAU20551Y
title_short Multi-omics analysis reveals the mechanism for galactose metabolism in mutant Streptococcus thermophilus IMAU20551Y
title_sort multi omics analysis reveals the mechanism for galactose metabolism in mutant streptococcus thermophilus imau20551y
topic Streptococcus thermophilus
Galactose metabolism
Genomic analysis
Transcriptome analysis
url http://www.sciencedirect.com/science/article/pii/S2665927125000486
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