Biomarker fatty acids of permafrost peat plateaus of the Komi Republic

Abstract

A method for the determination of biomarker fatty acids (C12–C28) in soils’ lipids that involves their extraction, chemical modification and gas chromatographic detection with a flame ionization detector (GC-FID) has been developed. This methodology allows to evaluate the content of free fatty acids in the soil (not bound to lipids). The extraction of lipids and fatty acids from the soil was optimized according to the following parameters: the type of extractant, the ratio of soil mass to extractant during extraction, and the duration of extraction. 13 biomarker carboxylic acids, that characterize groups of gram-negative and gram-positive bacteria and which are related to common bacterial markers, were identified by chromatography-mass spectrometry in permafrost peat plateaus. It is shown that the acids С14:0 to С20:0are contained in the studied peats in both free and bound form, while the acids С22:0to С28:0are contained mainly in a free form. The developed method allows determining the content of fatty acids in the soil in the range from 10 to 1000 mg/kg. The detection limit is 2 mg/kg, the relative error is 5–15%, the weight of the soil sample is 1–2 g, and the total duration of the analysis is 4 hours.