Carbon storage is a common strategy of soil microbes to cope with resource fluctuations. Fungi use neutral lipids (triacylglycerols, TAGs) for storage, which can be quantified via their derived fatty acids (NLFAs). NLFAs specific to bacteria can also be abundant in soils, but are rarely analysed as soil bacteria are assumed to not store TAGs. Instead, bacterial NLFAs are thought to derive from degraded phospholipids (diacylglycerols, DAGs), and thus indicate bacterial necromass, but this interpretation lacks evidence. In this perspective, we synthesise knowledge from the literature and our own experimental results on the origin of soil bacterial NLFAs. In sum, we provide evidence that bacterial NLFAs are predominantly derived from TAGs used for carbon storage: (1) Several pure culture studies provide evidence for TAG production in selected bacterial isolates. (2) Screening of genomes showed that wax ester synthase/diacylglycerol acyltransferases, which mediate the last step of TAG synthesis, are abundant in bacterial isolates from soil, suggesting a widespread genetic capability to produce TAGs. (3) We experimentally created conditions of excess labile carbon by adding isotopically labelled glucose to soil. Glucose-13C was rapidly allocated into bacterial NLFAs, with higher relative enrichment than phospholipid-derived fatty acids, indicating storage. (4) DAGs are not necessarily produced\uffe2\uff80\uff94and may only be intermediate compounds\uffe2\uff80\uff94during phospholipid degradation. We conclude that soil bacterial NLFAs are mainly derived from storage compounds, but a potential contribution from degraded phospholipids needs further validation. Isotopic labelling could resolve this, making NLFAs a valuable biomarker for microbial storage compounds in soil.
HighlightsBacterial NLFAs originate from triacylglycerols (TAGs) or degraded phospholipids
Neutral lipids are not necessarily produced during phospholipid degradation
Soil bacteria have the genetic potential to produce TAGs for storage
Rapid transfer of excess glucose-13C into soil bacterial NLFAs suggests storage
Bacterial NLFAs are markers for carbon storage rather than necromassarea.csv) Assignment of lipids that the measured fatty acids originate from (LipidClass.csv) An R script reproducing the calculations and plotting for Fig. 2 and Fig. S1 (pure_lipids.R) 2. Microbial pure culture fatty acid data data TIC area data of the PLFA, NLFA, and GLFA data from pure culture extracts (area.csv) Files needed for calculating the data and assigning taxonomic groups in the R code (weights.csv, C_atoms.csv, species_list.csv) An R script reproducing the calculations and plotting for Fig. 3, Fig. 4, Fig. S2, and Fig. S3 (pure_cultures.R) 3. Soil fatty acid data Absolute abundance data in nmol C g-1 dry weight of the PLFA, NLFA, and GLFA data from soil extracts (nmolC.csv) Taxonomic group assignments of fatty acids needed to run the R code (phylum.csv) An R script reproducing the calculations and plotting for Fig. 5, and Fig. S4 (soil.R)", "keywords": ["NLFA", "soil lipids", "soil fatty acid profiles", "phospholipid fatty acids", "GLFA"], "contacts": [{"organization": "Stefan, Gorka, Darcy, Sean, Horak, Julia, Imai, Bruna, Mohrlok, Moritz, Salas, Erika, Richter, Andreas, Schmidt, Hannes, Wanek, Wolfgang, Kaiser, Christina, Canarini, Alberto,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.5281/zenodo.8410341"}, {"rel": "self", "type": "application/geo+json", "title": "10.5281/zenodo.8410341", "name": "item", "description": "10.5281/zenodo.8410341", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.5281/zenodo.8410341"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2023-10-05T00:00:00Z"}}, {"id": "10.5281/zenodo.8410340", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-27T16:24:55Z", "type": "Dataset", "title": "Dataset for the article \"Beyond PLFA: Concurrent extraction of neutral and glycolipid fatty acids provides new insights into soil microbial communities\"", "description": "The following are data and code used for statistical analysis and figure plotting in the manuscript Gorka et al. (2023) 'Beyond PLFA: Concurrent extraction of neutral and glycolipid fatty acids provides new insights into soil microbial communities', Soil Biology and Biochemistry It contains the following files: 1. Pure lipid standard data Total ion chromatogram (TIC) area data (area.csv) Assignment of lipids that the measured fatty acids originate from (LipidClass.csv) An R script reproducing the calculations and plotting for Fig. 2 and Fig. S1 (pure_lipids.R) 2. Microbial pure culture fatty acid data data TIC area data of the PLFA, NLFA, and GLFA data from pure culture extracts (area.csv) Files needed for calculating the data and assigning taxonomic groups in the R code (weights.csv, C_atoms.csv, species_list.csv) An R script reproducing the calculations and plotting for Fig. 3, Fig. 4, Fig. S2, and Fig. S3 (pure_cultures.R) 3. Soil fatty acid data Absolute abundance data in nmol C g-1 dry weight of the PLFA, NLFA, and GLFA data from soil extracts (nmolC.csv) Taxonomic group assignments of fatty acids needed to run the R code (phylum.csv) An R script reproducing the calculations and plotting for Fig. 5, and Fig. S4 (soil.R)", "keywords": ["NLFA", "soil lipids", "soil fatty acid profiles", "phospholipid fatty acids", "GLFA"], "contacts": [{"organization": "Gorka Stefan, Sean Darcy, Julia Horak, Bruna Imai, Moritz Mohrlok, Erika Salas, Andreas Richter, Hannes Schmidt, Wolfgang Wanek, Christina Kaiser, Alberto Canarini,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.5281/zenodo.8410340"}, {"rel": "self", "type": "application/geo+json", "title": "10.5281/zenodo.8410340", "name": "item", "description": "10.5281/zenodo.8410340", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.5281/zenodo.8410340"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2023-10-05T00:00:00Z"}}, {"id": "11585/1016867", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-27T16:26:17Z", "type": "Journal Article", "created": "2024-12-03", "title": "Soil bacterial neutral lipid fatty acids: Markers for carbon storage or necromass?", "description": "Abstract
Carbon storage is a common strategy of soil microbes to cope with resource fluctuations. Fungi use neutral lipids (triacylglycerols, TAGs) for storage, which can be quantified via their derived fatty acids (NLFAs). NLFAs specific to bacteria can also be abundant in soils, but are rarely analysed as soil bacteria are assumed to not store TAGs. Instead, bacterial NLFAs are thought to derive from degraded phospholipids (diacylglycerols, DAGs), and thus indicate bacterial necromass, but this interpretation lacks evidence. In this perspective, we synthesise knowledge from the literature and our own experimental results on the origin of soil bacterial NLFAs. In sum, we provide evidence that bacterial NLFAs are predominantly derived from TAGs used for carbon storage: (1) Several pure culture studies provide evidence for TAG production in selected bacterial isolates. (2) Screening of genomes showed that wax ester synthase/diacylglycerol acyltransferases, which mediate the last step of TAG synthesis, are abundant in bacterial isolates from soil, suggesting a widespread genetic capability to produce TAGs. (3) We experimentally created conditions of excess labile carbon by adding isotopically labelled glucose to soil. Glucose-13C was rapidly allocated into bacterial NLFAs, with higher relative enrichment than phospholipid-derived fatty acids, indicating storage. (4) DAGs are not necessarily produced\uffe2\uff80\uff94and may only be intermediate compounds\uffe2\uff80\uff94during phospholipid degradation. We conclude that soil bacterial NLFAs are mainly derived from storage compounds, but a potential contribution from degraded phospholipids needs further validation. Isotopic labelling could resolve this, making NLFAs a valuable biomarker for microbial storage compounds in soil.
HighlightsBacterial NLFAs originate from triacylglycerols (TAGs) or degraded phospholipids
Neutral lipids are not necessarily produced during phospholipid degradation
Soil bacteria have the genetic potential to produce TAGs for storage
Rapid transfer of excess glucose-13C into soil bacterial NLFAs suggests storage
Bacterial NLFAs are markers for carbon storage rather than necromass