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Article Dans Une Revue Journal of Microbiological Methods Année : 2007

Tracing 2,4-D metabolism in Cupriavidus necator JMP134 with 13C-labelling technique and fatty acid profiling

Résumé

The use of stable isotope probing of fatty acid methyl esters (FAME-SIP) is a powerful tool to study the microorganisms involved in xenobiotic biodegradation in soil. Nevertheless, it is important to determine how representative these molecules are of microorganisms both qualitatively and quantitatively. Using Cupriavidus necator JMP134 as a simple experimental model, we showed that the 13C-labelling technique can be used both at a global (here defined as cellular, medium and CO2) and molecular level to study the metabolism of 2,4-Dichlorophenoxyacetic acid (2,4-D). Although isotopic fractionation among substrate, biomass and FAME were observed, this technique could be used when using a highly 13C-labelled substrate. Global 13C analyses gave similar results to those obtained with traditional 14C-labelling methods. After 10 days of incubation 59% of ring-C was mineralized and about 30% remained in the liquid medium. A maximum of 11% was incorporated into the biomass after 3 days. The assimilation yield of chain-C into the biomass was about half that of ring-C, suggesting a preferential use of chain-C for energy acquisition. Molecular analysis of the lipid fraction evidenced that the incorporation of the labelled 2,4-D did not correspond to a bioaccumulation of pesticide residues but to the metabolism of the 2,4-D carbons for FAME synthesis. Provided the labelling is located on the benzenic ring, the assessment of 13C-FAME is a robust method to quantify the incorporation of 13C into the whole microbial biomass. However, the variability of the 13C incorporation among FAME due to physiological processes has to be considered in complex biological systems. The coupling of bulk and molecular studies with a simple model as C. necator JMP134 is a good approach for testing FAME-SIP.

Dates et versions

hal-01191970 , version 1 (02-09-2015)

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Thomas Lerch, Marie-France Dignac, Enrique Barriuso, Gérard Bardoux, André A. Mariotti. Tracing 2,4-D metabolism in Cupriavidus necator JMP134 with 13C-labelling technique and fatty acid profiling. Journal of Microbiological Methods, 2007, 71 (2), pp.162-174. ⟨10.1016/j.mimet.2007.08.003⟩. ⟨hal-01191970⟩
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