Detection of archaeal diether lipid by gas chromatography from humus and peat

A suitable method based on gas chromatography to detect the diphytanylglyce rol diether (archaeol), the domain membrane lipid of Archaea, was used to t race the presence of Archaea in humus and peat. The elution of the standard used (1,2-di-O-hexadecyl-rac-glycerol) was reproducible above a concentrat ion of 1 mg 1(-1) (2 ng peak(-1)), which was the detection limit of the met hod. No archaeol was detected from the humus sample. This was verified usin g polymerase chain reaction (PCR) with primers specific to archaeal 16S rDN A gene region. Spiking the humus with an archaeon, Halobacterium salinarum, gave a positive response for both methods. This indicated that there were no Archaea in the specific hum-us sample. The peat samples used for extract ion of diether lipids were first characterized for their CH4 production rat e, which indicated the presence of methanogens (Archaea). With unlimited ac cess to CO2/H-2, the methane production rate peaked between 15 and 25 cm. T he archaeol could be identified from all depths sampled. The maximum archae ol concentration was at 20 cm, indicating the highest methanogenic populati on density at this depth. This is in accordance with the results from the m ethane production estimates.