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Spona-Friedl, M. ; Braun, A.* ; Huber, C.* ; Eisenreich, W.* ; Griebler, C. ; Kappler, A.* ; Elsner, M.

Substrate-dependent CO2 fixation in heterotrophic bacteria revealed by stable isotope labelling.

FEMS Microbiol. Ecol. 96:fiaa080 (2020)
Publ. Version/Full Text Postprint DOI PMC
Open Access Green
Virtually all heterotrophs incorporate carbon dioxide by anaplerotic fixation. Little explored, however, is the interdependency of pathways and rates of CO2 fixation on the concurrent usage of organic substrate(s). Potentially, this could reveal which substrates out of a pool of dissolved organic carbon are utilised by environmental microorganisms. To explore this possibility, Bacillus subtilis W23 was grown in a minimal medium with normalised amounts of either glucose, lactate or malate as only organic substrates, each together with 1 g/L (NaHCO3)-C-13. Incorporation of (HCO3)-C-13 - was traced by elemental analysis-isotope ratio mass spectrometry of biomass and gas chromatography-mass spectrometry of protein-derived amino acids. Until the late logarithmic phase, C-13 incorporation into the tricarboxylic acid cycle increased with time and occurred via [4-C-13]oxaloacetate formed by carboxylation of pyruvate. The levels of C-13 incorporation were highest for growth on glucose and lowest on malate. Incorporation of C-13 into gluconeogenesis products was mainly detected in the lactate and malate experiment, whereas glucose down-regulated this path. A proof-of-principle study with a natural groundwater community confirmed the ability to determine incorporation from (HCO3)-C-13 - by natural communities leading to specific labelling patterns. This underlines the potential of the labelling approach to characterise carbon sources of heterotrophic microorganisms in their natural environments.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords Heterotrophic Co2 Fixation ; Isotope Labelling ; Organic Substrate Use ; Dissolved Organic Matter ; Bacterial Substrate Usage ; Isotope Analysis; Bicarbonate Assimilation; Pyruvate-carboxylase; Bacillus-subtilis; (co2)-c-13; Mechanism; Perturbation; Metabolism; Insights; Malate; Growth
ISSN (print) / ISBN 0168-6496
e-ISSN 1574-6941
Journal FEMS Microbiology Ecology
Quellenangaben Volume: 96, Issue: 6, Pages: , Article Number: fiaa080 Supplement: ,
Publisher Wiley
Publishing Place Oxford
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Institute of Groundwater Ecology (IGOE)