Directory UMM :Data Elmu:jurnal:S:Soil Biology And Chemistry:Vol32.Issue8-9.Aug2000:
Soil Biology & Biochemistry 32 (2000) 1241±1249
www.elsevier.com/locate/soilbio
Ester-linked polar lipid fatty acid pro®les of soil microbial
communities: a comparison of extraction methods and evaluation
of interference from humic acids
Pernille Nielsen, Sùren O. Petersen*
Danish Institute of Agricultural Sciences, Department of Crop Physiology and Soil Science, P.O. Box 50, DK-8830 Tjele, Denmark
Received 7 July 1999; received in revised form 23 December 1999; accepted 21 February 2000
Abstract
Analyses of polar lipid fatty acids isolated from soil are frequently used for characterization of microbial communities, and
any interference from fatty acids derived from dead organic material is assumed to be negligible. We studied the initial
extraction of lipid material from eight dierent soils and from puri®ed humic acids using four dierent combinations of solvent
(chloroform or dichloromethane), methanol and buer (potassium phosphate, pH 7.4 or sodium citrate, pH 4). The quantitative
yields of polar lipid fatty acids (PLFA) and PLFA composition of soils and humic acids were compared with absorbance spectra
(200±850 nm) of lipid extracts for evaluation of extraction eciency and potential interference. Chloroform + citrate buer
generally gave the highest, and dichloromethane + phosphate buer the lowest PLFA yields, and it was estimated that
www.elsevier.com/locate/soilbio
Ester-linked polar lipid fatty acid pro®les of soil microbial
communities: a comparison of extraction methods and evaluation
of interference from humic acids
Pernille Nielsen, Sùren O. Petersen*
Danish Institute of Agricultural Sciences, Department of Crop Physiology and Soil Science, P.O. Box 50, DK-8830 Tjele, Denmark
Received 7 July 1999; received in revised form 23 December 1999; accepted 21 February 2000
Abstract
Analyses of polar lipid fatty acids isolated from soil are frequently used for characterization of microbial communities, and
any interference from fatty acids derived from dead organic material is assumed to be negligible. We studied the initial
extraction of lipid material from eight dierent soils and from puri®ed humic acids using four dierent combinations of solvent
(chloroform or dichloromethane), methanol and buer (potassium phosphate, pH 7.4 or sodium citrate, pH 4). The quantitative
yields of polar lipid fatty acids (PLFA) and PLFA composition of soils and humic acids were compared with absorbance spectra
(200±850 nm) of lipid extracts for evaluation of extraction eciency and potential interference. Chloroform + citrate buer
generally gave the highest, and dichloromethane + phosphate buer the lowest PLFA yields, and it was estimated that