title: Profiling of soil fatty acids using comprehensive two-dimensional gas chromatography with mass spectrometry detection.
abstract: Profiling of phospholipid fatty acids (PLFA) represents a challenging goal for distinguishing the diversity of microbial communities and biomass in the complex and heterogeneous soil ecosystem. Comprehensive two-dimensional gas chromatography (GC×GC) coupled with simultaneous flame ionisation and mass spectrometry detection was applied as a culture-independent method for PLFA profiling of microbial classification in forest soil. A number of column sets were evaluated for the GC×GC separation of fatty acid methyl esters (FAME). Due to better isomeric separation and compound patterns on the 2D contour plot, an apolar-polar column combination was selected for soil microbial PLFA characterisation. A comprehensive view of PLFA composition with carbon chain length varying from 12 to 20 was observed in forest soil samples, with the commonly reported bacterial FAME of iso-/anteiso-, methyl-branched-, cyclopropyl-, and hydroxyl-substituted FA identified by their mass spectral and retention time according to authentic standards. Notably, some uncommon oxygenated FAME were found in high abundance and were further characterised by GC×GC coupled with high resolution mass spectrometry. This tentatively revealed geometric pairs of methyl 9,10-epoxyoctadecanoate isomers.
authors.affiliation: Australian Centre for Research on Separation Science, School of Chemistry, Monash University, Wellington Road, Clayton, VIC 3800, Australia.
authors.forename: Annie Xu
authors.initials: AX
authors.lastname: Zeng
authors.forename: Sung-Tong
authors.initials: ST
authors.lastname: Chin
authors.forename: Antonio
authors.initials: A
authors.lastname: Patti
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Marriott
mesh_terms: D005227:Fatty Acids / Q000032:analysis* / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D005227:Fatty Acids; D012987:Soil
keywords: Accurate mass spectrometry; Bioactive fatty acid; High resolution separation; Quadrupole time of flight mass spectrometry; Soil microbial fatty acid