Organic Geochemistry [Biogéohimie Moléculaire]

Abstract :

Anaerobic ammonium oxidation (anammox) is a major process of bioavailable nitrogen removal frommarine systems. Previously, a bacteriohopanetetrol (BHT) isomer, with unknown stereochemistry, elut-ing later than BHT when examined by high performance liquid chromatography (HPLC), was detectedin ‘Ca.Scalindua profunda’ and proposed as a biomarker for anammox in marine paleo-environments.However, the utility of this BHT isomer as an anammox biomarker is hindered by the fact that four other,non-anammox, bacteria are also known to produce a late-eluting BHT stereoisomer. The stereochemistryinAcetobacter pasteurianus,Komagataeibacter xylinusandFrankiasp.was known to be 17b,21b(H), 22R,32R,33R,34R(BHT-34R). The stereochemistry of the late-eluting BHT inMethylocella palustriswasunknown. To determine if marine anammox bacteria produce a unique BHT isomer, we studied theBHT distributions and stereochemistry of known BHT isomer producers and of previously unscreenedmarine (‘Ca.Scalindua brodeae’) and freshwater (‘Ca.Brocadia spp.’) anammox bacteria, using HPLCand gas chromatographiy (GC) analysis of acetylated BHTs and ultra high performance liquid chromatog-raphy (UHPLC)-high resolution mass spectrometry (HRMS) analysis of non-acetylated BHTs. The 34Rstereochemistry was confirmed for the BHT isomers inCa.Brocadia sp. andMethylocella palustris.However, ‘Ca.Scalindua spp.’ synthesises a stereochemically distinct BHT isomer, with still unconfirmedstereochemistry (BHT-x). Only GC analysis of acetylated BHT and UHPLC analysis of non-acetylated BHTdistinguished between late-eluting BHT isomers. Acetylated BHT-xand BHT-34Rco-elute when exam-ined by HPLC. As BHT-xis currently only known to be produced by ‘Ca.Scalindua spp.’, it may be a bio-marker for marine anammox.

 

Reference :

Rachel Schwartz-Narbonne, Philippe Schaeffer, Ellen C. Hopmans, Margot Schenesse,E. Alex Charlton, D. Martin Jones, Jaap S. Sinninghe Damsté, Muhammad Farhan Ul Haque, Mike S.M. Jetten, Sabine K. Lengger, J. Colin Murrell, Philippe Normand, Guylaine H.L. Nuijten, Helen M. Talbot, Darci Rush

A unique bacteriohopanetetrol stereoisomer of marine anammox

Organic Géochemistry, Accepted 21 February 2020, DOI : https://doi.org/10.1016/j.orggeochem.2020.103994

 

Contact chercheur :

Philippe Schaeffer, Laboratoire de Biogéochimie Moléculaire, Institut de Chimie (UMR 7177).