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<p>Microbial synthesis of (+)-valencene from agricultural wastes such as cornstalk will serve as a sustainable alternative to the traditional plant extraction method. In this study, <i>Rhodobacter sphaeroides</i> strains were engineered for valencene production through a stepwise manner: (1) heterologous expression of <i>Callitropsis nootkatensis</i> valencene synthase (CnVS) in combination with <i>phaB/gdhA/ladH</i> knockouts enabled <i>de novo</i> biosynthesis of valencene from glucose at a titer of 34.21 ± 3.1&#xa0;mg/L; (2) a quorum-sensing promoter P<sub><i>cer</i></sub> to decouple growth and production phase further improved the valencene titer to 80.75 ± 3.0&#xa0;mg/L; and (3) transposon-mediated genomic integration of the heterologous mevalonate pathway to enhance farnesyl pyrophosphate supply resulted in 120.53 ± 10.34&#xa0;mg/L valencene. Subsequently, the alkali-pretreated cornstalk hydrolysate was used as the substrate, and 100.51 ± 14.15&#xa0;mg/L valencene was achieved under the optimized carbon-to-nitrogen ratio. In summary, the engineered <i>R. sphaeroides</i> offers an alternative mean to valorize the cheap agricultural waste for high-value valencene production.</p>

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Systematic engineering to enhance valencene production in Rhodobacter sphaeroides

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年9月20日

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  • Zhizhen Li,
  • Wenhao Li,
  • Xinyu Gao,
  • Wenming Yao,
  • Zhenqian Zhu,
  • Xueyi Luo,
  • Yang Zhang,
  • Jifeng Yuan

摘要

Microbial synthesis of (+)-valencene from agricultural wastes such as cornstalk will serve as a sustainable alternative to the traditional plant extraction method. In this study, Rhodobacter sphaeroides strains were engineered for valencene production through a stepwise manner: (1) heterologous expression of Callitropsis nootkatensis valencene synthase (CnVS) in combination with phaB/gdhA/ladH knockouts enabled de novo biosynthesis of valencene from glucose at a titer of 34.21 ± 3.1 mg/L; (2) a quorum-sensing promoter Pcer to decouple growth and production phase further improved the valencene titer to 80.75 ± 3.0 mg/L; and (3) transposon-mediated genomic integration of the heterologous mevalonate pathway to enhance farnesyl pyrophosphate supply resulted in 120.53 ± 10.34 mg/L valencene. Subsequently, the alkali-pretreated cornstalk hydrolysate was used as the substrate, and 100.51 ± 14.15 mg/L valencene was achieved under the optimized carbon-to-nitrogen ratio. In summary, the engineered R. sphaeroides offers an alternative mean to valorize the cheap agricultural waste for high-value valencene production.