Aerobic-anaerobic transition boosts poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in Rhodospirillum rubrum: the key role of carbon dioxide
Abstract Background Microbially produced bioplastics are specially promising materials since they can be naturally synthesized and degraded, making its end-of-life management more amenable to the environment. A prominent example of these new materials are polyhydroxyalkanoates. These polyesters serv...
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| Format: | Article |
| Language: | English |
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BMC
2023-03-01
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| Series: | Microbial Cell Factories |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s12934-023-02045-x |
| _version_ | 1827770320878043136 |
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| author | Manuel S. Godoy Santiago R. de Miguel M. Auxiliadora Prieto |
| author_facet | Manuel S. Godoy Santiago R. de Miguel M. Auxiliadora Prieto |
| author_sort | Manuel S. Godoy |
| collection | DOAJ |
| description | Abstract Background Microbially produced bioplastics are specially promising materials since they can be naturally synthesized and degraded, making its end-of-life management more amenable to the environment. A prominent example of these new materials are polyhydroxyalkanoates. These polyesters serve manly as carbon and energy storage and increase the resistance to stress. Their synthesis can also work as an electron sink for the regeneration of oxidized cofactors. In terms of biotechnological applications, the co-polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate), or PHBV, has interesting biotechnological properties due to its lower stiffness and fragility compared to the homopolymer poly(3-hydroxybutyrate) (P3HB). In this work, we explored the potentiality of Rhodospirillum rubrum as a producer of this co-polymer, exploiting its metabolic versatility when grown in different aeration conditions and photoheterotrophically. Results When shaken flasks experiments were carried out with limited aeration using fructose as carbon source, PHBV production was triggered reaching 29 ± 2% CDW of polymer accumulation with a 75 ± 1%mol of 3-hydroxyvalerate (3HV) (condition C2). Propionate and acetate were secreted in this condition. The synthesis of PHBV was exclusively carried out by the PHA synthase PhaC2. Interestingly, transcription of cbbM coding RuBisCO, the key enzyme of the Calvin-Benson-Bassham cycle, was similar in aerobic and microaerobic/anaerobic cultures. The maximal PHBV yield (81% CDW with 86%mol 3HV) was achieved when cells were transferred from aerobic to anaerobic conditions and controlling the CO2 concentration by adding bicarbonate to the culture. In these conditions, the cells behaved like resting cells, since polymer accumulation prevailed over residual biomass formation. In the absence of bicarbonate, cells could not adapt to an anaerobic environment in the studied lapse. Conclusions We found that two-phase growth (aerobic-anaerobic) significantly improved the previous report of PHBV production in purple nonsulfur bacteria, maximizing the polymer accumulation at the expense of other components of the biomass. The presence of CO2 is key in this process demonstrating the involvement of the Calvin-Benson-Bassham in the adaptation to changes in oxygen availability. These results stand R. rubrum as a promising producer of high-3HV-content PHBV co-polymer from fructose, a PHBV unrelated carbon source. |
| first_indexed | 2024-03-11T12:36:54Z |
| format | Article |
| id | doaj.art-b9c3a82edd1a4fc7b426651d5a4c2740 |
| institution | Directory Open Access Journal |
| issn | 1475-2859 |
| language | English |
| last_indexed | 2024-03-11T12:36:54Z |
| publishDate | 2023-03-01 |
| publisher | BMC |
| record_format | Article |
| series | Microbial Cell Factories |
| spelling | doaj.art-b9c3a82edd1a4fc7b426651d5a4c27402023-11-05T12:33:01ZengBMCMicrobial Cell Factories1475-28592023-03-0122111610.1186/s12934-023-02045-xAerobic-anaerobic transition boosts poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in Rhodospirillum rubrum: the key role of carbon dioxideManuel S. Godoy0Santiago R. de Miguel1M. Auxiliadora Prieto2Polymer Biotechnology Lab, Biological Research Centre Margarita Salas, Spanish National Research Council (CIB-CSIC)Polymer Biotechnology Lab, Biological Research Centre Margarita Salas, Spanish National Research Council (CIB-CSIC)Polymer Biotechnology Lab, Biological Research Centre Margarita Salas, Spanish National Research Council (CIB-CSIC)Abstract Background Microbially produced bioplastics are specially promising materials since they can be naturally synthesized and degraded, making its end-of-life management more amenable to the environment. A prominent example of these new materials are polyhydroxyalkanoates. These polyesters serve manly as carbon and energy storage and increase the resistance to stress. Their synthesis can also work as an electron sink for the regeneration of oxidized cofactors. In terms of biotechnological applications, the co-polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate), or PHBV, has interesting biotechnological properties due to its lower stiffness and fragility compared to the homopolymer poly(3-hydroxybutyrate) (P3HB). In this work, we explored the potentiality of Rhodospirillum rubrum as a producer of this co-polymer, exploiting its metabolic versatility when grown in different aeration conditions and photoheterotrophically. Results When shaken flasks experiments were carried out with limited aeration using fructose as carbon source, PHBV production was triggered reaching 29 ± 2% CDW of polymer accumulation with a 75 ± 1%mol of 3-hydroxyvalerate (3HV) (condition C2). Propionate and acetate were secreted in this condition. The synthesis of PHBV was exclusively carried out by the PHA synthase PhaC2. Interestingly, transcription of cbbM coding RuBisCO, the key enzyme of the Calvin-Benson-Bassham cycle, was similar in aerobic and microaerobic/anaerobic cultures. The maximal PHBV yield (81% CDW with 86%mol 3HV) was achieved when cells were transferred from aerobic to anaerobic conditions and controlling the CO2 concentration by adding bicarbonate to the culture. In these conditions, the cells behaved like resting cells, since polymer accumulation prevailed over residual biomass formation. In the absence of bicarbonate, cells could not adapt to an anaerobic environment in the studied lapse. Conclusions We found that two-phase growth (aerobic-anaerobic) significantly improved the previous report of PHBV production in purple nonsulfur bacteria, maximizing the polymer accumulation at the expense of other components of the biomass. The presence of CO2 is key in this process demonstrating the involvement of the Calvin-Benson-Bassham in the adaptation to changes in oxygen availability. These results stand R. rubrum as a promising producer of high-3HV-content PHBV co-polymer from fructose, a PHBV unrelated carbon source.https://doi.org/10.1186/s12934-023-02045-xRhodospirillum rubrumPoly(3-hydroxybutyrate-co-3-hydroxyvalerate)PHBVPurple nonsulfur bacteriaCalvin-Benson-Bassham cycleElectron sink |
| spellingShingle | Manuel S. Godoy Santiago R. de Miguel M. Auxiliadora Prieto Aerobic-anaerobic transition boosts poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in Rhodospirillum rubrum: the key role of carbon dioxide Microbial Cell Factories Rhodospirillum rubrum Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV Purple nonsulfur bacteria Calvin-Benson-Bassham cycle Electron sink |
| title | Aerobic-anaerobic transition boosts poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in Rhodospirillum rubrum: the key role of carbon dioxide |
| title_full | Aerobic-anaerobic transition boosts poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in Rhodospirillum rubrum: the key role of carbon dioxide |
| title_fullStr | Aerobic-anaerobic transition boosts poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in Rhodospirillum rubrum: the key role of carbon dioxide |
| title_full_unstemmed | Aerobic-anaerobic transition boosts poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in Rhodospirillum rubrum: the key role of carbon dioxide |
| title_short | Aerobic-anaerobic transition boosts poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in Rhodospirillum rubrum: the key role of carbon dioxide |
| title_sort | aerobic anaerobic transition boosts poly 3 hydroxybutyrate co 3 hydroxyvalerate synthesis in rhodospirillum rubrum the key role of carbon dioxide |
| topic | Rhodospirillum rubrum Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV Purple nonsulfur bacteria Calvin-Benson-Bassham cycle Electron sink |
| url | https://doi.org/10.1186/s12934-023-02045-x |
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