title: Microbial lipids reveal carbon assimilation patterns on hydrothermal sulfide chimneys.
abstract: Sulfide 'chimneys' characteristic of seafloor hydrothermal venting are diverse microbial habitats. ¹³C/¹²C ratios of microbial lipids have rarely been used to assess carbon assimilation pathways on these structures, despite complementing gene- and culture-based approaches. Here, we integrate analyses of the diversity of intact polar lipids (IPL) and their side-chain δ¹³C values (δ¹³ C(lipid)) with 16S rRNA gene-based phylogeny to examine microbial carbon flow on active and inactive sulfide structures from the Manus Basin. Surficial crusts of active structures, dominated by Epsilonproteobacteria, yield bacterial δ¹³C(lipid) values higher than biomass δ¹³C (total organic carbon), implicating autotrophy via the reverse tricarboxylic acid cycle. Our data also suggest δ¹³C(lipid) values vary on individual active structures without accompanying microbial diversity changes. Temperature and/or dissolved substrate effects - likely relating to variable advective-diffusive fluxes to chimney exteriors - may be responsible for differing ¹³C fractionation during assimilation. In an inactive structure, δ¹³C(lipid) values lower than biomass δ¹³C and a distinctive IPL and 16S rRNA gene diversity suggest a shift to a more diverse community and an alternate carbon assimilation pathway after venting ceases. We discuss here the potential of IPL and δ¹³C(lipid) analyses to elucidate carbon flow in hydrothermal structures when combined with other molecular tools.
authors.affiliation: MARUM Center for Marine Environmental Sciences & Department of Geosciences, University of Bremen, Bremen, D-28359, Germany.
authors.forename: Eoghan P
authors.initials: EP
authors.lastname: Reeves
authors.forename: Marcos Y
authors.initials: MY
authors.lastname: Yoshinaga
authors.forename: Petra
authors.initials: P
authors.lastname: Pjevac
authors.forename: Nadine I
authors.initials: NI
authors.lastname: Goldenstein
authors.forename: Jörg
authors.initials: J
authors.lastname: Peplies
authors.forename: Anke
authors.initials: A
authors.lastname: Meyerdierks
authors.forename: Rudolf
authors.initials: R
authors.lastname: Amann
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bach
authors.forename: Kai-Uwe
authors.initials: KU
authors.lastname: Hinrichs
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D017753:Ecosystem; D020565:Epsilonproteobacteria / Q000378:metabolism; D060086:Hydrothermal Vents / Q000737:chemistry / Q000382:microbiology*; D008055:Lipids / Q000032:analysis*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013440:Sulfides / Q000378:metabolism*
chemical_list: D008055:Lipids; D012336:RNA, Ribosomal, 16S; D013440:Sulfides; D002244:Carbon