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Background <p>Exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) play important roles in industrial applications. The type of carbon source affects both the production and composition of EPSs. However, the molecular mechanisms underlying this regulation in <i>Pediococcus pentosaceus</i> remain poorly understood. This study explores the effects of different carbon sources on the EPS biosynthesis pathway and monosaccharide composition in <i>P. pentosaceus</i> LL-07, with particular emphasis on transcriptional regulation.</p> Results <p>EPS yields were similar under glucose, fructose, or lactose (<i>p &gt;</i> 0.05). However, RNA-Seq revealed distinct gene expression patterns. KEGG and GO analyses showed activation of carbohydrate metabolism and EPS-related pathways. Lactose significantly upregulated genes in the Leloir pathway (<i>galK</i>, <i>galT</i>, <i>galE</i>), nucleotide sugar biosynthesis (<i>pgm</i>, <i>galU</i>), and key EPS cluster genes (<i>wzz</i>, <i>wzc</i>, <i>gt0590</i>). This suggests extensive transcriptional remodeling. Monosaccharide analysis of purified EPS showed that all EPSs mainly contained glucose, galactose, and mannose. However, their composition varied with the carbon source: EPSs from lactose and glucose had more galactose, while fructose-derived EPSs contained more mannose. This matched the transcriptional data. GEPS-1 exhibits better in vitro antioxidant activity and thermogravimetric properties.</p> Conclusion <p>Carbon source selection alters the transcriptional profile of <i>P. pentosaceus</i> LL-07, affecting the monosaccharide composition, in vitro antioxidant activity, and thermogravimetric properties of its EPSs. These findings connect sugar metabolism to EPS structural changes. They provide a potential strategy to tailor microbial polysaccharides through substrate engineering for applications in functional foods and biotechnology.</p>

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Carbon source–dependent transcriptomic regulation and monosaccharide remodeling of exopolysaccharide biosynthesis in Pediococcus pceusentosa LL-07

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年10月28日

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  • Kuan Lu,
  • Xueya Wang,
  • Ying Zhou,
  • Qiujin Zhu

摘要

Background

Exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) play important roles in industrial applications. The type of carbon source affects both the production and composition of EPSs. However, the molecular mechanisms underlying this regulation in Pediococcus pentosaceus remain poorly understood. This study explores the effects of different carbon sources on the EPS biosynthesis pathway and monosaccharide composition in P. pentosaceus LL-07, with particular emphasis on transcriptional regulation.

Results

EPS yields were similar under glucose, fructose, or lactose (p > 0.05). However, RNA-Seq revealed distinct gene expression patterns. KEGG and GO analyses showed activation of carbohydrate metabolism and EPS-related pathways. Lactose significantly upregulated genes in the Leloir pathway (galK, galT, galE), nucleotide sugar biosynthesis (pgm, galU), and key EPS cluster genes (wzz, wzc, gt0590). This suggests extensive transcriptional remodeling. Monosaccharide analysis of purified EPS showed that all EPSs mainly contained glucose, galactose, and mannose. However, their composition varied with the carbon source: EPSs from lactose and glucose had more galactose, while fructose-derived EPSs contained more mannose. This matched the transcriptional data. GEPS-1 exhibits better in vitro antioxidant activity and thermogravimetric properties.

Conclusion

Carbon source selection alters the transcriptional profile of P. pentosaceus LL-07, affecting the monosaccharide composition, in vitro antioxidant activity, and thermogravimetric properties of its EPSs. These findings connect sugar metabolism to EPS structural changes. They provide a potential strategy to tailor microbial polysaccharides through substrate engineering for applications in functional foods and biotechnology.