title: Carbon roadmap from syngas to polyhydroxyalkanoates in Rhodospirillum rubrum.
abstract: The gasification of organic waste materials to synthesis gas (syngas), followed by microbial fermentation, provides a significant resource for generating bioproducts such as polyhydroxyalkanoates (PHA). The anaerobic photosynthetic bacterium, Rhodospirillum rubrum, is an organism particularly attractive for the bioconversion of syngas into PHAs. In this study, a quantitative physiological analysis of R. rubrum was carried out by implementing GC-MS and HPLC techniques to unravel the metabolic pathway operating during syngas fermentation that leads to PHA production. Further, detailed investigations of the central carbon metabolites using (13) C-labelled substrate showed significant CO2 assimilation (of 40%) into cell material and PHA from syngas carbon fraction. By a combination of quantitative gene expression and enzyme activity analyses, the main role of carboxylases from the central carbon metabolism in CO2 assimilation was shown, where the Calvin-Benson-Bassham cycle (CBB) played a minor role. This knowledge sheds light about the biochemical pathways that contribute to synthesis of PHA during syngas fermentation being valuable information to further optimize the fermentation process.
authors.affiliation: Department of Environmental Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), 28040, Madrid, Spain.
authors.forename: O
authors.initials: O
authors.lastname: Revelles
authors.affiliation: Department of Environmental Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), 28040, Madrid, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Tarazona
authors.affiliation: Department of Environmental Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), 28040, Madrid, Spain.
authors.forename: J L
authors.initials: JL
authors.lastname: García
authors.affiliation: Department of Environmental Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), 28040, Madrid, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Prieto
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D019735:Carbon-Carbon Ligases / Q000378:metabolism; D005285:Fermentation / Q000502:physiology*; D008401:Gas Chromatography-Mass Spectrometry; D010788:Photosynthesis / Q000502:physiology*; D054813:Polyhydroxyalkanoates / Q000378:metabolism*; D012247:Rhodospirillum rubrum / Q000378:metabolism*
chemical_list: D054813:Polyhydroxyalkanoates; D002245:Carbon Dioxide; D002244:Carbon; D019735:Carbon-Carbon Ligases