SAR92 clade bacteria are potentially important DMSP degraders and sources of climate-active gases in marine environments.
SAR92 clade bacteria are potentially important DMSP degraders and sources of climate-active gases in marine environments.
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DOI：
10.1128/mbio.01467-23
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发表时间：
2023-12-19
期刊：
影响因子：
6.4
通讯作者：
Zhang, Xi-Ying
中科院分区：
文献类型：
--
作者：
He, Xiao-Yan;Liu, Ning-Hua;Liu, Ji-Qing;Peng, Ming;Teng, Zhao-Jie;Gu, Tie-Ji;Chen, Xiu-Lan;Chen, Yin;Wang, Peng;Li, Chun-Yang;Todd, Jonathan D.;Zhang, Yu-Zhong;Zhang, Xi-Ying
二甲基磺基丙酸酯(DMSP)是地球上含量最丰富的有机硫分子之一，可被海洋细菌分解，通过裂解和/或去甲基化途径释放气候活性气体。海洋SAR92分支是近海海水中含量丰富的伽马变形杆菌的寡养类群，但它们分解DMSP的能力尚未得到测试。本研究中从近海海水中分离到的3株SAR92分支菌株和SAR92代表菌株HTCC2207均能分解DMSP作为碳源。所有SAR92分支菌株都具有产生二甲基硫化物(DMS)的DMSP裂解酶活性，它们的基因组编码一个批准的DddD DMSP裂解酶。相比之下，只有HTCC2207和两个分离的菌株含有DMSP去甲基酶dmdA基因，并可能同时去甲基化和裂解DMSP以产生甲硫醇(Mesh)和DMS。在含有dddD和dmdA的SAR92分支菌株中，DMSP底物可诱导这些基因的转录。生物信息学分析表明，含有和转录DddD和DmdA的SAR92分支细菌广泛分布于全球海洋，尤其是极地地区。这项研究强调了SAR92类寡养菌是DMSP的潜在重要分解者，也是海洋环境中气候活性气体MESH和DMS的来源，特别是在极地地区。海洋细菌对二甲基磺酸丙酯(DMSP)的分解代谢对全球硫循环和气候有重要影响。然而，大多数寡营养细菌群的成员是否以及如何参与海洋环境中的DMSP新陈代谢在很大程度上仍不清楚。在这项研究中，通过对可培养菌株的鉴定，我们揭示了沿海海水中丰富的伽马蛋白细菌SAR92分支细菌可以通过DMSP裂解酶DddD介导的裂解途径和/或DMSP去甲基酶DmdA介导的去甲基化途径降解DMSP，产生气候活性气体二甲硫醚和甲硫醇。此外，我们还发现，能够分解DMSP的SAR92分支细菌在全球海洋中广泛分布。这些结果表明，SAR92分支细菌是海洋环境中被忽视的DMSP潜在的重要降解者和气候活性气体的来源，有助于更好地理解寡营养细菌在海洋DMSP降解中的作用和机制。
Dimethylsulfoniopropionate (DMSP) is one of Earth’s most abundant organosulfur molecules, which can be catabolized by marine bacteria to release climate-active gases through the cleavage and/or demethylation pathways. The marine SAR92 clade is an abundant oligotrophic group of Gammaproteobacteria in coastal seawater, but their ability to catabolize DMSP is untested. Three SAR92 clade strains isolated from coastal seawater in this study and the SAR92 representative strain HTCC2207 were all shown to catabolize DMSP as a carbon source. All the SAR92 clade strains exhibited DMSP lyase activity producing dimethylsulfide (DMS) and their genomes encoded a ratified DddD DMSP lyase. In contrast, only HTCC2207 and two isolated strains contained the DMSP demethylase dmdA gene and potentially simultaneously demethylated and cleaved DMSP to produce methanethiol (MeSH) and DMS. In SAR92 clade strains with dddD and dmdA, transcription of these genes was inducible by DMSP substrate. Bioinformatic analysis indicated that SAR92 clade bacteria containing and transcribing DddD and DmdA were widely distributed in global oceans, especially in polar regions. This study highlights the SAR92 clade of oligotrophic bacteria as potentially important catabolizers of DMSP and sources of the climate-active gases MeSH and DMS in marine environments, particularly in polar regions. Catabolism of dimethylsulfoniopropionate (DMSP) by marine bacteria has important impacts on the global sulfur cycle and climate. However, whether and how members of most oligotrophic bacterial groups participate in DMSP metabolism in marine environments remains largely unknown. In this study, by characterizing culturable strains, we have revealed that bacteria of the SAR92 clade, an abundant oligotrophic group of Gammaproteobacteria in coastal seawater, can catabolize DMSP through the DMSP lyase DddD-mediated cleavage pathway and/or the DMSP demethylase DmdA-mediated demethylation pathway to produce climate-active gases dimethylsulfide and methanethiol. Additionally, we found that SAR92 clade bacteria capable of catabolizing DMSP are widely distributed in global oceans. These results indicate that SAR92 clade bacteria are potentially important DMSP degraders and sources of climate-active gases in marine environments that have been overlooked, contributing to a better understanding of the roles and mechanisms of the oligotrophic bacteria in oceanic DMSP degradation.
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