Phospholipid fatty acid (PLFA) extracted from environmental samples describe the microbial community pattern and are sensitive to monitor and quantify shifts in the microbial community. Linkage with the stable isotope technique adds a functional perspective and is frequently used to quantify carbon turnover in microbial communities and detect physiological changes. Here we present a PLFA extraction method by using an organic solvent water mixture, followed by lipid separation based on solid-phase extraction and an alkaline methylation. Finally, we provide a protocol for the carbon stable isotope measurements of the extracted fatty acid methyl esters (FAMEs) by gas chromatograph–isotope ratio mass spectrometer (GC-IRMS) and calculation of concentration and δ13CVPDB values.
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The authors would like to thank all the coworkers and students for critical questions and comments when conducting PLFA extraction and GC-IRMS measurements, which over the years improved the protocol. The County of Lower Austria, NÖ Wirtschafts- und Tourismusfonds (WST3-F-5031245/003-2018) is acknowledged for funding.
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