The soil microorganisms as complex communities are the leading participants of the bio-geochemistry cycling of C and other nutrients. And phospholipids fatty acids (PLFAs) can serve as an important indicator of the viable microorganisms since they exist in all types of microbial membranes with constant quantity and fast turning-over rate, and they can respond promptly to the variations in environmental factors. Therefore, the relative simple and valuable PLFAs techniques have been utilized widely to investigate the characteristics of soil microorganisms.
The conception, nomenclatures, types, and characteristics of PLFAs are introduced in this paper. Different extraction processes for PLFAs and total soil fatty acid methyl esters (TSFAMEs) are sketched. At the same time, the comparison of extraction procedures between PLFAs and TSFAMEs is drawn. The possible problems that are likely to occur during the extraction processes are discussed in detail. The PLFAs-associated techniques such as the MIDI, GC-MS and HPLC-ESI-MS are also recommended here for the interpretation of PLFAs implications. In addition, this paper specifies the practical applications of PLFAs to the studies of soil microbial biomass, microbial communities and microbial metabolic conditions, as well as the effect of agricultural management on the microbial charactereristics. Some other applications are also summed up, for instantce, ecosystem recovery study and 13C-labeling technique.
Meanwhile, some limitations by using PLFAs as an indicator are figured out as well. For example, PLFAs can’t be used to distinguish the specific microbial communities in the native soils clearly in some cases. Nor can they be used to evaluate the fungal biomass correctly due to the uncertain structures of different microorganisms. PLFAs analysis can do nothing about Archaea either. Moreover, the results from different PLFAs extraction methods vary significantly and are easily interfered by other organic compounds in soil matrix. The soil samples for PLFAs analysis must be stored at -80℃ or lyophiled because of oxidation effects.
It is thereby suggested that in order to elucidate clearly the metabolic pathway and the structure of native microbial consortiums, PLFAs techniques should be employed together with other molecular biological techniques when necessary.