Direct Production of Bio-Recalcitrant Carboxyl-Rich Alicyclic Molecules Evidenced in a Bacterium-Induced Steroid Degradation Experiment.
Direct Production of Bio-Recalcitrant Carboxyl-Rich Alicyclic Molecules Evidenced in a Bacterium-Induced Steroid Degradation Experiment.
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DOI：
10.1128/spectrum.04693-22
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发表时间：
2023-02-06
影响因子：
3.7
通讯作者：
中科院分区：
文献类型：
--
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富羧基脂环族分子（CRAM）是一种高度不饱和的化合物，广泛分布于水环境和沉积物中。这个分子组被广泛认为是一个主要的替代品的柠檬酸有机物质，但其直接生物合成仍然不清楚。类固醇是一种典型的人为污染物，以前曾被认为是CRAM的前体;然而，缺乏支持这一假设的实验证据。在此，将类固醇降解细菌睾丸酮丛毛单胞菌ATCC 11996在补充有作为唯一碳源的睾酮（典型类固醇）的液体培养基中孵育90天。提取睾酮诱导的代谢产物（TIM）进行分子表征，并在接种天然沿海微生物组合后的额外90天孵育期间检查生物利用度。结果表明，使用超高分辨率质谱法将1，775个分子式（MF）分配给TIM，其中66.99%归类为CRAM类成分。一个很大的比例的TIM呼吸或转化过程中额外的90天的海水孵育，然而，638 MF的TIM持续或增加孵育过程中。在638个MFs中，有394个通常被分配在中国南海的天然深层海水样品（深度为500至2，000 m）中。与成熟的睾酮降解途径的催化剂相比，我们编制了一份生物难降解的MF和潜在化学结构的列表，其中一些与CRAM具有结构同源性。这些结果表明，直接微生物生产的生物难降解的CRAM从类固醇激素，并表明，一些生物的CRAM抵抗微生物的分解，可能有助于水生难降解的溶解有机物（DOM）池。重要CRAM是操作上定义的DOM基团，包含羧基化和稠合脂环结构的复杂混合物。这组DOM在海洋环境中主要以难降解DOM为特征。然而，复杂的CRAM的起源仍然不清楚。在这项研究中，我们证明了睾酮（一种典型的类固醇）可以通过单一细菌菌株转化为生物难降解的CRAM，并观察到一些CRAM高度抵抗微生物降解。通过分子比较和筛选，提出了类固醇诱导的CRAM的潜在化学结构。这项研究建立了类固醇和生物难降解的CRAM之间的生物学联系，它提供了一个新的视角来解释陆生污染物在水生环境中的命运。
Carboxyl-rich alicyclic molecules (CRAM) are highly unsaturated compounds extensively distributed throughout aquatic environments and sediments. This molecular group is widely referred to as a major proxy of recalcitrant organic materials, but its direct biosynthesis remains unclear. Steroids are a typical anthropogenic contaminant and have been previously suggested to be precursors of CRAM; however, experimental evidence to support this hypothesis is lacking. Here, a steroid-degrading bacterium, Comamonas testosteroni ATCC 11996, was incubated in a liquid medium supplemented with testosterone (a typical steroid) as the sole carbon source for 90 days. Testosterone-induced metabolites (TIM) were extracted for molecular characterization and to examine the bioavailability during an additional 90-day incubation after inoculation with a natural coastal microbial assemblage. The results showed that 1,775 molecular formulas (MFs) were assigned to TIM using ultrahigh-resolution mass spectrometry, with 66.99% categorized as CRAM-like constituents. A large fraction of TIM was respired or transformed during the additional 90-day seawater incubation; nevertheless, 638 MFs of the TIM persisted or increased during incubation. Among the 638 MFs, 394 were commonly assigned in natural deep seawater samples (depths of 500 to 2,000 m) from the South China Sea. Compared to the catabolites of the well-established testosterone degradation pathway, we compiled a list of bio-refractory MFs and potential chemical structures, some of which shared structural homology with CRAM. These results demonstrated direct microbial production of bio-refractory CRAM from steroid hormones and indicated that some of the biogenic CRAM resisted microbial decomposition, potentially contributing to the aquatic refractory dissolved organic matter (DOM) pool. IMPORTANCE CRAM are an operationally defined DOM group comprising a complex mixture of carboxylated and fused alicyclic structures. This DOM group is majorly characterized as refractory DOM in the marine environment. However, the origins of the complex CRAM remain unclear. In this study, we demonstrated that testosterone (a typical steroid) could be transformed into bio-refractory CRAM by a single bacterial strain and observed that some of the CRAM highly resisted microbial degradation. Through molecular comparison and screening, potential chemical structures of steroid-induced CRAM were suggested. This study established the biological connection between steroids and bio-refractory CRAM, and it provides a novel perspective explaining the fate of terrestrial contaminants in aquatic environments.
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影响因子：
2.7
作者：
Dittmar, Thorsten;Koch, Boris;Kattner, Gerhard
通讯作者：
Kattner, Gerhard
影响因子：
6.8
作者：
Barbosa, Isabel R.;Nogueira, Antonio J. A.;Soares, Amadeu M. V. M.
通讯作者：
Soares, Amadeu M. V. M.
影响因子：
9.8
作者：
Frena, Morgana;Bataglion, Giovana A.;Madureira, Luiz A. S.
通讯作者：
Madureira, Luiz A. S.
影响因子：
3.7
作者：
Wang PH;Lee TH;Ismail W;Tsai CY;Lin CW;Tsai YW;Chiang YR
通讯作者：
Chiang YR
影响因子：
11.4
作者：
Kolpin, DW;Furlong, ET;Buxton, HT
通讯作者：
Buxton, HT