A unique bacteriohopanetetrol stereoisomer of marine anammox

Characterization of diverse bacteriohopanepolyols in a permanently stratified, hyper-euxinic lake

“…Notably, stereoisomers of BHT were not observed in any of the samples, despite 'late-eluting BHT isomers' being associated with modern marine water column suboxia/anoxia, as well as bacterial anaerobic oxidation of ammonium (anammox) activity (Sáenz et al, 2011;Wakeham et al, 2012;Kharbush et al, 2013;Rush et al, 2014;Matys et al, 2017Matys et al, , 2019Schwartz-Narbonne et al, 2020;van Kemenade et al, 2022). The lack of BHT isomer(s) supports previous studies which suggest that the isomerization of BHT and ratios of BHT to its isomer(s) are more indicative of anammox activity rather than simply suboxia/anoxia.…”

“…Additionally, it has been suggested that the ratio of bacteriohopanetetrol (BHT) to its isomer(s) in sediments can be used as a proxy for suboxicanoxic water column conditions (Sáenz et al, 2011). The presence of specific BHT isomers has more recently been associated with anaerobic ammonium-oxidation (anammox), an important microbial process in the nitrogen cycle (e.g., Rush et al, 2014;Matys et al, 2017;Schwartz-Narbonne et al, 2020;van Kemenade et al, 2022). Many studies now postulate that C-2 methylated hopanoids (originally thought to be indicative of oxygenic photosynthesis; Summons et al, 1999) are produced in response to myriad environmental stressors (e.g., changes in pH, redox, nutrient availability, solar irradiance), combinations of which are still being revealed (see review by Newman et al, 2016 and references therein;Matys et al, 2019a).…”

Reviews and syntheses: Review of proxies for low-oxygen paleoceanographic reconstructions

“…However, ladderanes do not preserve well (Rush et al, 2011) and, thus far, the oldest sedimentary record containing ladderanes extends only 140 kyr (Jaeschke et al, 2009). More recently, a unique bacteriohopanepolyol (BHP) biomarker for marine anammox 'Candidatus Scalindua profunda' was identified (Schwartz-Narbonne et al, 2020): a bacteriohopanetetrol isomer with unknown stereochemistry, BHT-x (Rush et al, 2014;Schwartz-Narbonne et al, 2020), has strongly depleted δ 13 C values in sediments consistent with fractionation associated with the reductive acetyl-CoA pathway used by anammox (Hemingway et al, 2018;Lengger et al, 2019), and has a distinct niche in the nitrite maximum of stratified water column settings (e.g., Matys et al, 2017). In comparison to ladderanes, BHPs preserve well and BHT has been detected in samples as old as ca.…”

Reply on RC1

“…However, ladderanes do not preserve well (Rush et al, 2011) and, thus far, the oldest sedimentary record containing ladderanes extends only 140 kyr (Jaeschke et al, 2009). More recently, a unique bacteriohopanepolyol (BHP) biomarker for marine anammox 'Candidatus Scalindua profunda' was identified (Schwartz-Narbonne et al, 2020): a bacteriohopanetetrol isomer with unknown stereochemistry, BHT-x (Rush et al, 2014;Schwartz-Narbonne et al, 2020), has strongly depleted δ 13 C values in sediments consistent with fractionation associated with the reductive acetyl-CoA pathway used by anammox (Hemingway et al, 2018;Lengger et al, 2019), and has a distinct niche in the nitrite maximum of stratified water column settings (e.g., Matys et al, 2017). In comparison to ladderanes, BHPs preserve well and BHT has been detected in samples as old as ca.…”