Anaerobic ammonium-oxidising bacteria: A biological source of the bacteriohopanetetrol stereoisomer in marine sediments

Abstract

Bacterially-derived bacteriohopanepolyols (BHPs) are abundant, well preserved lipids in modern and paleo-environments. Bacteriohopanetetrol (BHT) is a ubiquitously produced BHP while its less common stereoisomer (BHT isomer) has previously been associated with anoxic environments; however, its biological source remained unknown. We investigated the occurrence of BHPs in Golfo Dulce, an anoxic marine fjord-like enclosure located in Costa Rica. The distribution of BHT isomer in four sediment cores and a surface sediment transect closely followed the distribution of ladderane fatty acids, unique biomarkers for bacteria performing anaerobic ammonium oxidation (anammox). This suggests that BHT isomer and ladderane lipids likely shared the same biological source in Golfo Dulce. This was supported by examining the BHP lipid compositions of two enrichment cultures of a marine anammox species ('Candidatus Scalindua profunda'), which were found to contain both BHT and BHT isomer. Remarkably, the BHT isomer was present in higher relative abundance than BHT. However, a non-marine anammox enrichment contained only BHT, which explains the infrequence of BHT isomer observations in terrestrial settings, and indicates that marine anammox bacteria are likely responsible for at least part of the environmentally-observed marine BHT isomer occurrences.Given the substantially greater residence time of BHPs in sediments, compared to ladderanes, BHT isomer is a potential biomarker for past anammox activity.3

Dark carbon fixation in the Arabian Sea oxygen minimum zone contributes to sedimentary organic carbon (SOM)

“…S. profunda’ detected by HTGC‐MS (Figure S2b). In addition to being present in ‘ Ca Scalindua sp.’ anammox bacteria, BHT is a ubiquitous lipid common to many bacteria, BHT', however, is specific to Ca Scalindua sp.’ in marine environments (Rush et al, ). The δ 13 C values of BHT and BHT' were identical within the error of analysis (‐49 and ‐48 ‰, respectively; Table ), indicating identical fractionation and thus biosynthetic pathways for both lipids.…”

The Bacteriohopanepolyol Inventory of Novel Aerobic Methane Oxidising Bacteria Reveals New Biomarker Signatures of Aerobic Methanotrophy in Marine Systems

“…However, as adenosylhopane is an intermediate in the biosynthesis of all other side-chain extended BHPs [94], other sources cannot be entirely excluded. BHT isomer, a biomarker for anaerobic ammonium oxidation [70], was found in high concentrations in GD (previously reported in [70]), as well as in the PM sediments, which underlie the Peruvian OMZ, where anammox is known to be an important process [95], and where BHT isomer has previously been reported from the water column within the OMZ [90]. The most abundant of the three regular amino-BHPs in the CH 4 -influenced marine sediments was aminotriol, which is not source-specific (e.g., [48]).…”

“…10 m) water depth [69]. GD sediments were collected along a transect from 10 to 140 m water depth in March 2008, as described in [70]. …”

Biomarkers in the stratified water column of the Landsort Deep (Baltic Sea)

“…The source of BHT II is not fully resolved yet. It was recently related to planctomycetes, especially those performing anaerobic ammonium oxidation (anammox) in sediments (Rush et al, 2014). Anammox bacteria can also be traced by 10-me16 : 0 PLFA and ladderane PLFAs (not studied here; Sinninghe Damsté et al, 2005;Schubert et al, 2006).…”