Application of ¹³C-labeled PLFA analysis in soil microbial ecology studies

Analysis of phospholipid fatty acids (PLFA) is an effective non-culture-based technique for information on living soil microbial community. PLFA is an important component of microbial cell membranes. Microbes can synthesize this special PLFA through various biochemical pathways hence some PLFA can be used as biomarker for a microbial community. When coupled with stable isotope ¹³C-labeled (¹³C-PLFA) technique, PLFA can be used to identify in situ structures of soil microbial communities. This can also be used to explore soil microbial functional communities responsible for metabolic processes of soil carbon sources in soil ecosystem, thus providing abundant information about microbial interactions in complex communities. This technique has the potential for wide future applications. The principle of ¹³C-PLFA technique is as follows: 1) adding ¹³C-rich substrates to the soils assimilated by some members of the soil microbial community; 2) extracting and purifying PLFA from soil substrate mixtures; 3) determining ¹³C value of PLFA using gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS); and 4) deriving required information by comparative analysis. This study introduced the principle of ¹³C-PLFA technique and reviewed the applications of ¹³C-PLFA in the fields of photosynthetic carbon utilization by rhizosphere microorganisms, priming effects of soil organic matter decomposition and mineralization, microbial oxidation of methane, degradation of organic pollutants and microbial utilization of exogenous simple and complicated carbon sources. The limitations and application potentials of this technique were also discussed. It was concluded that ¹³C-PLFA method was an excellent way of providing insight into the relations between microbial community composition and soil biogeochemical cycle.