Table 3.

Fatty acids used as taxonomic biomarkers (adapted from [298].

Fatty Acid	Category	Reference
Mono-Unsaturated Fatty Acids (MUFA)
16:1ω7c	Bacteria Bacillariophyceae (diatoms) Cyanophyceae (cyanobacteria) Prymnesiophyceae	[245,274,292,305]
16:1ω5c	mycorrhizal fungi	[306]
16:1ω8c	Type I methanotrophs (gamma-proteobacteria)	[307,308]
17:1	Cyanobacteria	[309]
17:1ω6c (up to 60%)	Desulfobulbus, Desulforhabdus, Desulforhopalus (sulphate reducing bacteria)	[310]
18:1ω9c	Chlorophyceae (green algae) Cyanophyceae Dinophyceae Prymnesiophyceae Gram-positive bacteria	[245,274,292,305,311]
18:1ω7c	Bacillariophyceae (up to 10-fold more 18:1ω7c than 18:1ω9c) Cryptophyceae Cyanophyceae (less amount than 18:1ω9c) Prymnesiophyceae	[245,274,292]
18:1ω7t	Gram-negative bacteria	[311]
18:1ω8c	Type II methanotrophs (alpha-proteobacteria)	[307,308]
Hydroxy substituted Fatty Acids (OH FA)
(e.g., 3-OH 10:0)	Gram-negative bacteria	[312]
Cyclopropyl saturated Fatty Acids (cyFA)
(e.g., cyclo17:0, cyclo19:0)	Gram-negative bacteria, anaerobic bacteria	[313,314]
Cyclo17:0ω5,6	Desulfosarcina/Desulfococcus (sulphate reducing bacteria)	[310]
Iso- and anteiso-branched Fatty Acids
(e.g., iso-15:0, anteiso-17:0) iso-17:1ω7c	Gram-positive bacteria Sulphate reducing bacteria Desulfovibrio sp. (sulphate reducing bacteria)	[313,314,315,316]
Methyl-branched Fatty Acids (10-Me FA)
10-Me 18:0 10-Me 16:0 2-Me 17:0	Actinomycetales (Actinobacteria) Desulfobacter sp.- sulphate reducing bacteria Cyanobacteria	[309,315,316,317]
Furan Fatty Acids
Fu18:2ω6, Fu17:2 ω5 and ω6	Dehalococcoides sp.	[318]
Polyunsaturated Fatty Acids (PUFA)
16:2ω7	Bacillariophyceae	[245]
16:2ω6	Chlorophyta	[245]
16:2ω4	Bacillariophyceae Prasinophyceae	[245,279]
16:3ω4	Bacillariophyceae	[245,279]
16:3ω3	Chlorophyta	[245]
16:4ω3	Chlorophyceae Prasinophyceae	[245]
16:4ω1	Bacillariophyceae (diatoms)	[245,279]
18:2ω6	Chlorophyta Cyanophyceae (freshwater) Dinophyceae Prymnesiophyceae Fungi	[245,274,292,305,313,314]
18:3ω6	Cyanophyceae (freshwater) Saprophytic fungi	[274,314,319]
18:3ω3	Chlorophyceae Crypophyceae Cyanophyceae Dinophyceae Prasinophyceae Prymnesiophyceae	[245,274,292]
18:4ω3	Most groups (both marine and freshwater)	[245,274,292]
18:5ω3	Dynophyceae	[245]
20:4ω6	Bacillariophyceae Rhodophyceae	[245]
20:5ω3	Bacillariophyceae Cryptophyceae Dinophyceae Pavlovophyceae Rhodophyceae	[245,292]
22:5ω3	Bacillariophyceae Cryptophyceae Prasinophyceae	[245]
22:6ω3	Bacillariophyceae Cryptophyceae Dinophyceae Haptophyta (Prymnesiophyceae and Pavlovophyceae)	[245,274,292]