Abstract
The current opinion and position paper highlights (1) correct assignation of indicator phospholipid fatty acids (PLFA), (2) specificity and recycling of PLFA in microorganisms, and (3) complete extraction and detection of PLFA. The straight-chain PLFA 14:0, 15:0, 16:0, and 17:0 occur in all microorganisms, i.e., also in fungi and not only in bacteria. If the phylum Actinobacteria is excluded from the group of Gram-positive bacteria, all remaining bacteria belong to the bacterial phylum Firmicutes, which should be considered. The PLFA 16:1ω5 should be used as an indicator for the biomass of arbuscular mycorrhizal fungi (AMF) as there is no experimental evidence that they occur in marked amounts in Gram-negative bacteria. Fungal PLFA should embrace the AMF-specific 16:1ω5. In the presence of plants, ergosterol should be used instead of the PLFA 18:2ω6,9 and 18:1ω9 as fungal indicators for Mucoromycotina, Ascomycota, and Basidiomycota. The majority of indicator PLFA are not fully specific for a certain microbial group. This problem might be intensified by recycling processes during decomposition to an unknown extent. Soil handling and extraction conditions should be further optimized. The reliability and accuracy of gas chromatographic separation need to be regularly checked against unintentional variations. PLFA analysis will still be of interest over the next decades as an important independent control of DNA-based methods.
Highlights
Phospholipid fatty acids (PLFA) are the main components of cell membranes in all organisms other than archaea and do not occur in storage components (Zelles 1999)
Soil bacteria consist of Gram-negative (G-) and Grampositive (G +) bacteria, the latter formed by the two bacterial phyla Firmicutes and Actinobacteria
These changes were often accompanied by significant changes in the composition of the main microbial groups according to PCA, the shifts in the contribution of single phospholipid fatty acids (PLFA) to total PLFA were small (Zelles 1999; Hamer et al 2008)
Summary
Phospholipid fatty acids (PLFA) are the main components of cell membranes in all organisms other than archaea and do not occur in storage components (Zelles 1999). The total PLFA concentration is used as an indicator for microbial biomass in soil (Frostegård et al 1991; Joergensen and Emmerling 2006), largely consisting of viable but non-culturable organisms (Zelles 1999). This contrasts neutral lipid fatty acids (NLFA), which are storage components, especially in fungi, and give interesting information on the nutritional status of fungi (Bååth 2003). The objective of the current opinion and position paper is to highlight several persisting problems: (1) correct assignation of indicator PLFA, (2) specificity and recycling of PLFA in microorganisms, and (3) complete extraction and detection of PLFA
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
