Just another CropScience weblog

Gas chromatography of fatty acids extracted from soil

The gas chromatographie of lipids was practiced in “rhizosphere ecology”. The results were presented by WeberV and BrynerS.

Membranes of organisms are composed of lipids. These lipids are only produced in a living organismis, so the lipid concentration is a index for the activity of organisms. Different organisms have a different lipid composition. Lipid chromatography helps to get general idea about organism community present or to detect an organism with special FAs (e.g. mycorrhiza or gram negative bacteria (C16:1). For the gas chromatography of fatty acids an internal standard and chloroform-methanol are added to soil samples. After centrifugation the liquid phase is transferred to a new vial and then NaCl is added. After another centrifugation the clear phase (with the lipids) was taken out, filtered and evaporated.The fatty acids (FAs) are burnt with H2 inside the chromatograph. With this of ions are due to the temperature produced. The amount of charged ions is then detected. The separation of FAs happens due to chain lengths and saturation by time. The Peaks in the output of the chromatograph represent different FAs and the area of peak reflects the amount of FA. The real amount of the FA is afterwards calculated in relation to the internal standard.
All in all there should be more bacteria (= more lipids) at the plant roots followed by the rhizosphere and the bulk soil.

If you use a molecular method or lipid chromatographie depends on your objective. If you want to investigate the acitvity of organisms or functional groups you should use lipid chromatographie. If you want to detect a specific organism a molecular method would be better. But molecular methods do not differentiate between dead and living organisms because they rely on DNA.

November 10th, 2007
Topic: Crop Science, Plant nutrition Tags: None

≡ Leave a Reply

You must be logged in to post a comment.