Stable carbon isotope evidence for the microbial origin of C14C18 n-alkanoic acids in soils

Abstract

Abstract-In order to delineate the origin of soil fatty acids, crop soil samples have been incubated for 21 days in vitro either with unlabelled or 13 C-labelled glucose.

Isotope evidence for soil organic carbon pools with distinct turnover rates—II. Humic substances

“…Details on sample setting and mineral content are described elsewhere (Balabane and Balesdent, 1992). Artificial labelling: soil samples from a crop field (Grignon, France) were sterilized with γ rays, then incubated for 21 days in the dark at pF 2 at 28°C with water from the same field containing either Dglucose (δ 13 C = -10.60‰) or " 13 C-D-glucose" (δ 13 C ~ +500‰) (Lichtfouse et al, 1995a).…”

Soil organic matter dynamics: a biological perspective derived from the use of compound‐specific isotopes studies

“…On the one hand molecules can be stabilized in the soil by a range of processes, including (i) recalcitrance (molecules that require too much energy to decompose), (ii) inaccessibility to decomposition which includes the attachment of molecules to mineral surfaces and the spatial separation of decomposers and substrates (Sollins et al 1996;Torn et al 1997;Kaiser et al 2002;Kogel-Knabner 2002;von Luetzow et al 2006). On the other hand, molecules can be newly synthesized by soil organisms and mimic the stability of plant-derived molecules (Lichtfouse et al 1995;Gleixner et al 2001;Simpson et al 2002;Kelleher and Simpson 2006;Kindler et al 2006;Simpson et al 2007;Miltner et al 2009). Recalcitrance of chemical compounds is very obvious from oil and coal that originate from plant material and consist of lipids like alkanes and polyaromatic structures like polyaromatic hydrocarbons (PAH), respectively (Engel and Macko 1993).…”

Gas chromatography coupled to mass spectrometry for analyses of organic compounds and biomarkers as tracers for geological, environmental, and forensic research

“…mycose) are also examples of microbial-derived compounds commonly used to study the fungal community in several soil samples [e. g., 157,161,259,260]. The use of GC -IRMS in soil science is significant and encompasses the investigation of origins (plant versus microbes) of homologous lipids (e. g., fatty acids, n-alkanes, n-alkanols) [261] and the fate and cycling of organic compounds by different microorganisms [e. g., 262] through the application of 13 C-labelled compounds (e. g., glucose), as well as the determination of individual turnover rates of specific lipid and non-lipid compounds (e. g., carbohydrates, lignin, lipids, and N-containing compounds) [263].…”