Direct linking of microbial populations to specific biogeochemical processes by 13C-labelling of biomarkers

Glycerol ether biomarkers and their carbon isotopic compositions in a cold seep carbonate chimney from the Shenhu area, northern South China Sea

“…In AOM environments, the incorporation of methane derived from carbon into these lipids is indicated by their very low δ 13 C values. Significant amounts of 13 C depleted Ar were reported from all methane oxidizing archaea habitat studies, with δ 13 C values varying between 120‰ and 61‰ [15]. Strongly 13 C depleted Ar is found in the Shenhu carbonate chimney, indicating AOM processes in this region.…”

“…2,6,11,15-tetramethylhexadecane (crocetane) and 2,6,10,15, 19-pentamethyleicosane (PMI) and their unsaturated homologues; and (2) the isoprenoidal glycerol ethers, such as archaeol (Ar) and sn2-/sn3-/di-hydroxyarchaeol [15]. In AOM environments, bacterial biomarkers co-occurring with 13 C-depleted archaeal lipids are evident by their highly depleted carbon isotope composition compared with the source carbon. Therefore, the significant 13 C depletion indicates the methane carbon incorporation into microbial biomass [41][42][43][44].…”

“…16S rDNA clone libraries and/or fluorescence in situ hybridization, as well as lipid biomarker analyses [15]. In contrast to marine dissolved inorganic carbon, which typically has a δ 13 C value close to 0 [16], δ 13 C signatures of AOM derived lipids are extremely 13 C depleted with δ 13 C values lower than 50‰ [15], even down to 130‰ [17]. Therefore, typical anaerobic-related lipid biomarkers and their compound-specific stable carbon isotopes can be used to trace AOM communities in modern and ancient environments [12,15].…”

“…Lipid biomarkers are constituents of the cytoplasmic membrane surrounding each cell, which allow the identification of dominant microbes and, if combined with a compound specific stable carbon isotope analysis, their carbon fixation pathways [13][14][15]. The identification of AOM communities was achieved using independent molecular techniques, i.e.…”

Phase Preference by Active, Acetate-Utilizing Bacteria at the Rifle, CO Integrated Field Research Challenge Site

“…For example, stable isotope incorporation into macromolecules from environmental samples has been used to target metabolically active bacteria by monitoring phospholipids (3,4,5) This principle of purifying isotopically-labeled nucleic acids and coupling to molecular ecology techniques was presented by 3 Radajewski et al, using 13 C-methanol to identify the active degraders in soil samples (6). Similar studies using the SIP techniques have been applied to a variety of natural systems using substrates ranging from methanol, methyl bromide, phenol, naphthalene, phenanthrene, benzoate, and salicylate (7,8,9).…”