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<p>Polyhydroxyalkanoates (PHAs) are promising biodegradable polymers synthesized by bacteria, yet their widespread application remains limited by production cost and yield. To achieve cost-effective and efficient production of PHA, PHA synthesis-related genes (<i>phaC</i><sub><i>R</i></sub> <i>and phaAB</i><sub><i>R</i></sub>) from <i>Rhodoligotrophos defluvii</i> lm1<sup>T</sup> were cloned into plasmids under different promoters (P<sub>tac</sub>, P<sub>Cn</sub>, and lac-tac) and expressed in <i>Escherichia coli</i> DH5α with a <i>ptsG</i> gene knockout to relieve carbon catabolite repression in this study. Among the recombinant strains, L3/<i>ΔptsG</i>, containing the P<sub>Cn</sub> promoter, achieved the highest PHA yield (36.25 wt%) using 27&#xa0;g/L glucose and 1.5&#xa0;g/L sodium propionate as carbon sources. The produced polymer was identified as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by gas chromatography and nuclear magnetic resonance spectroscopy, exhibiting favorable monomer composition, molecular weight, and thermal stability (T<sub>d5</sub> = 271 ℃). These findings demonstrate that combining promoter optimization with dual carbon-source feeding enables efficient PHBV production in engineered <i>E. coli</i>, offering a viable route for cost-effective bioplastic synthesis.</p>

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Promoter-driven enhancement of PHBV synthesis in recombinant Escherichia coli using glucose and propionate as carbon sources

  • 期刊论文

  • 发表日期：

    2026年3月17日

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  • Zhao-song Huang,
  • Cheng-jiao Yu,
  • Zi-miao Yan,
  • Chang-feng Miao,
  • Ling-yi Hou,
  • Peng-fei Gu,
  • Xiang-yu Fan,
  • Qiang Li

摘要

Polyhydroxyalkanoates (PHAs) are promising biodegradable polymers synthesized by bacteria, yet their widespread application remains limited by production cost and yield. To achieve cost-effective and efficient production of PHA, PHA synthesis-related genes (phaCR and phaABR) from Rhodoligotrophos defluvii lm1T were cloned into plasmids under different promoters (Ptac, PCn, and lac-tac) and expressed in Escherichia coli DH5α with a ptsG gene knockout to relieve carbon catabolite repression in this study. Among the recombinant strains, L3/ΔptsG, containing the PCn promoter, achieved the highest PHA yield (36.25 wt%) using 27 g/L glucose and 1.5 g/L sodium propionate as carbon sources. The produced polymer was identified as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by gas chromatography and nuclear magnetic resonance spectroscopy, exhibiting favorable monomer composition, molecular weight, and thermal stability (Td5 = 271 ℃). These findings demonstrate that combining promoter optimization with dual carbon-source feeding enables efficient PHBV production in engineered E. coli, offering a viable route for cost-effective bioplastic synthesis.