Abstract Anaerobic ammonium oxidation (anammox) is a major process of bioavailable nitrogen removal from marine systems. Previously, a bacteriohopanetetrol (BHT) isomer, with unknown stereochemistry, eluting later than BHT when examined by high performance liquid chromatography (HPLC), was detected in ‘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 stereochemistry in Acetobacter pasteurianus, Komagataeibacter xylinus and Frankia sp. was known to be 17β, 21β(H), 22R, 32R, 33R, 34R (BHT-34R). The stereochemistry of the late-eluting BHT in Methylocella palustris was unknown. To determine if marine anammox bacteria produce a unique BHT isomer, we studied the BHT distributions and stereochemistry of known BHT isomer producers and of previously unscreened marine (‘Ca. Scalindua brodeae’) and freshwater (‘Ca. Brocadia spp.’) anammox bacteria, using HPLC and gas chromatographiy (GC) analysis of acetylated BHTs and ultra high performance liquid chromatography (UHPLC)-high resolution mass spectrometry (HRMS) analysis of non-acetylated BHTs. The 34R stereochemistry was confirmed for the BHT isomers in Ca. Brocadia sp. and Methylocella palustris. However, ‘Ca. Scalindua spp.’ synthesises a stereochemically distinct BHT isomer, with still unconfirmed stereochemistry (BHT-x). Only GC analysis of acetylated BHT and UHPLC analysis of non-acetylated BHT distinguished between late-eluting BHT isomers. Acetylated BHT-x and BHT-34R co-elute when examined by HPLC. As BHT-x is currently only known to be produced by ‘Ca. Scalindua spp.’, it may be a biomarker for marine anammox.

中文翻译：

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一种独特的海洋厌氧氨氧化菌的立体异构体

摘要 厌氧氨氧化（anammox）是从海洋系统中去除生物可利用氮的主要过程。以前，在 'Ca 中检测到一种具有未知立体化学的 bacteriohopanetetrol (BHT) 异构体，在通过高效液相色谱 (HPLC) 检查时比 BHT 更晚洗脱。Scalindua profunda' 并被提议作为海洋古环境中厌氧氨氧化的生物标志物。然而，这种 BHT 异构体作为厌氧氨氧化生物标志物的效用受到以下事实的阻碍：其他四种非厌氧氨氧化细菌也已知会产生晚洗脱的 BHT 立体异构体。Acetobacter pasteurianus, Komagataeibacter xylinus 和 Frankia sp. 的立体化学。已知为 17β、21β(H)、22R、32R、33R、34R (BHT-34R)。Methylocella palustris 中晚洗脱 BHT 的立体化学未知。为了确定海洋厌氧氨氧化细菌是否产生独特的 BHT 异构体，我们研究了已知 BHT 异构体生产者和以前未筛选的海洋（'Ca. Scalindua brodeae'）和淡水（'Ca. Brocadia spp.'）厌氧氨氧化细菌的 BHT 分布和立体化学，使用 HPLC 和气相色谱 (GC) 分析乙酰化 BHT，以及超高效液相色谱 (UHPLC)-高分辨率质谱 (HRMS) 分析非乙酰化 BHT。Ca 中 BHT 异构体的 34R 立体化学得到证实。Brocadia sp. 和沼泽甲基藻。然而，'Ca。Scalinua spp.' 合成立体化学上不同的 BHT 异构体，但立体化学尚未确定 (BHT-x)。只有乙酰化 BHT 的 GC 分析和非乙酰化 BHT 的 UHPLC 分析区分了晚洗脱的 BHT 异构体。当通过 HPLC 检查时，乙酰化 BHT-x 和 BHT-34R 共流出。由于目前只知道 BHT-x 是由 'Ca 生产的。Scalindua spp.'，它可能是海洋厌氧氨氧化的生物标志物。