Development of an Engineered Bacterial Endophyte: Promoting Plant Growth Through Pyrroloquinoline Quinone (PQQ) Synthesis
Endophytic bacteria are a group of microorganisms that can intercellularly colonize plant hosts without causing apparent damage or disease. Our previous works found that a pyrroloquinoline quinone (PQQ)-producing endophyte could promote plant growth and systemic tolerance. To demonstrate this PQQ-pr...
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2025-01-01
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| author | Ti Fang Shou-Chen Lo Yu-Ning Yu Nga-Lai Sou Shih-Hsun Walter Hung Jian-Hau Peng En-Pei Isabel Chiang Chieh-Chen Huang |
| author_facet | Ti Fang Shou-Chen Lo Yu-Ning Yu Nga-Lai Sou Shih-Hsun Walter Hung Jian-Hau Peng En-Pei Isabel Chiang Chieh-Chen Huang |
| author_sort | Ti Fang |
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| description | Endophytic bacteria are a group of microorganisms that can intercellularly colonize plant hosts without causing apparent damage or disease. Our previous works found that a pyrroloquinoline quinone (PQQ)-producing endophyte could promote plant growth and systemic tolerance. To demonstrate this PQQ-producing endophyte’s beneficial role in plants, a set of five PQQ synthesis genes from <i>Gluconobacter oxydans</i> was introduced into both <i>Escherichia coli</i> JM109 and <i>Bacillus subtilis</i> RM125, a BsuM-deficient mutant of laboratory strain <i>B. subtilis</i> 168. Interestingly, both strains harboring the PQQ synthesis genes exhibited significantly higher optimal optical density than control strains. In a carbon flux analysis, both strains showed a noticeable increase in their citric acid, alpha-ketoglutaric acid, and succinic acid levels. Conversely, in <i>E. coli</i>, pyruvic acid, malic acid, and fumaric acid levels decreased. These results suggest that PQQ impacts various host species differently. Furthermore, the presence of PQQ in fermentation broth was also confirmed in the RM125 PQQ synthesis recombinant strain. Subsequent experiments by inoculating those <i>Bacillus</i> strains revealed that the laboratory host strain could function as an endophyte, and the PQQ transgenic strain could further promote the growth of <i>Arabidopsis thaliana</i> and increase the number of siliques. These findings confirm PQQ’s vital role in endophyte-mediated plant growth promotion and also suggest the potential of <i>B. subtilis</i> transformed with PQQ genes as an engineered endophyte for studying PQQ’s biological functions in plants. This research is a step forward in understanding how specific substances can beneficially influence plant growth and systemic tolerance through endophytic mechanisms. |
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| publishDate | 2025-01-01 |
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| spelling | doaj-art-c8fdf6fb3a514d9182a8aa9dcf11987f2025-08-20T02:04:02ZengMDPI AGMicroorganisms2076-26072025-01-0113229310.3390/microorganisms13020293Development of an Engineered Bacterial Endophyte: Promoting Plant Growth Through Pyrroloquinoline Quinone (PQQ) SynthesisTi Fang0Shou-Chen Lo1Yu-Ning Yu2Nga-Lai Sou3Shih-Hsun Walter Hung4Jian-Hau Peng5En-Pei Isabel Chiang6Chieh-Chen Huang7Department of Life Science, National Chung Hsing University, Taichung 402, TaiwanDepartment of Life Science, National Chung Hsing University, Taichung 402, TaiwanDepartment of Life Science, National Chung Hsing University, Taichung 402, TaiwanDepartment of Food Science and Biotechnology, National Chung Hsing University, Taichung 402, TaiwanDepartment of Life Science, National Chung Hsing University, Taichung 402, TaiwanDepartment of Food Science and Biotechnology, National Chung Hsing University, Taichung 402, TaiwanDepartment of Food Science and Biotechnology, National Chung Hsing University, Taichung 402, TaiwanDepartment of Life Science, National Chung Hsing University, Taichung 402, TaiwanEndophytic bacteria are a group of microorganisms that can intercellularly colonize plant hosts without causing apparent damage or disease. Our previous works found that a pyrroloquinoline quinone (PQQ)-producing endophyte could promote plant growth and systemic tolerance. To demonstrate this PQQ-producing endophyte’s beneficial role in plants, a set of five PQQ synthesis genes from <i>Gluconobacter oxydans</i> was introduced into both <i>Escherichia coli</i> JM109 and <i>Bacillus subtilis</i> RM125, a BsuM-deficient mutant of laboratory strain <i>B. subtilis</i> 168. Interestingly, both strains harboring the PQQ synthesis genes exhibited significantly higher optimal optical density than control strains. In a carbon flux analysis, both strains showed a noticeable increase in their citric acid, alpha-ketoglutaric acid, and succinic acid levels. Conversely, in <i>E. coli</i>, pyruvic acid, malic acid, and fumaric acid levels decreased. These results suggest that PQQ impacts various host species differently. Furthermore, the presence of PQQ in fermentation broth was also confirmed in the RM125 PQQ synthesis recombinant strain. Subsequent experiments by inoculating those <i>Bacillus</i> strains revealed that the laboratory host strain could function as an endophyte, and the PQQ transgenic strain could further promote the growth of <i>Arabidopsis thaliana</i> and increase the number of siliques. These findings confirm PQQ’s vital role in endophyte-mediated plant growth promotion and also suggest the potential of <i>B. subtilis</i> transformed with PQQ genes as an engineered endophyte for studying PQQ’s biological functions in plants. This research is a step forward in understanding how specific substances can beneficially influence plant growth and systemic tolerance through endophytic mechanisms.https://www.mdpi.com/2076-2607/13/2/293PQQpyrroloquinoline quinoneengineered endophyte<i>B. subtilis</i>biostimulantsgrowth promotion |
| spellingShingle | Ti Fang Shou-Chen Lo Yu-Ning Yu Nga-Lai Sou Shih-Hsun Walter Hung Jian-Hau Peng En-Pei Isabel Chiang Chieh-Chen Huang Development of an Engineered Bacterial Endophyte: Promoting Plant Growth Through Pyrroloquinoline Quinone (PQQ) Synthesis Microorganisms PQQ pyrroloquinoline quinone engineered endophyte <i>B. subtilis</i> biostimulants growth promotion |
| title | Development of an Engineered Bacterial Endophyte: Promoting Plant Growth Through Pyrroloquinoline Quinone (PQQ) Synthesis |
| title_full | Development of an Engineered Bacterial Endophyte: Promoting Plant Growth Through Pyrroloquinoline Quinone (PQQ) Synthesis |
| title_fullStr | Development of an Engineered Bacterial Endophyte: Promoting Plant Growth Through Pyrroloquinoline Quinone (PQQ) Synthesis |
| title_full_unstemmed | Development of an Engineered Bacterial Endophyte: Promoting Plant Growth Through Pyrroloquinoline Quinone (PQQ) Synthesis |
| title_short | Development of an Engineered Bacterial Endophyte: Promoting Plant Growth Through Pyrroloquinoline Quinone (PQQ) Synthesis |
| title_sort | development of an engineered bacterial endophyte promoting plant growth through pyrroloquinoline quinone pqq synthesis |
| topic | PQQ pyrroloquinoline quinone engineered endophyte <i>B. subtilis</i> biostimulants growth promotion |
| url | https://www.mdpi.com/2076-2607/13/2/293 |
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