DMSP Production by Coral-Associated Bacteria
DMSP Production by Coral-Associated Bacteria
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DOI：
10.3389/fmars.2022.869574
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发表时间：
2022-05-04
影响因子：
3.7
通讯作者：
Raina, Jean-Baptiste
中科院分区：
文献类型：
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作者：
Kuek, Felicity W. I.;Motti, Cherie A.;Raina, Jean-Baptiste
二甲基硫基丙酸盐（DMSP）是海洋硫循环中的重要分子，由珊瑚及其甲藻内共生体（共生藻科）大量产生。虽然已知珊瑚中含有能够分解二甲酚磺酰亚胺的细菌，但最近在沿海和深海环境中发现能够产生二甲酚磺酰亚胺的细菌，增加了细菌对珊瑚产生二甲酚磺酰亚胺的可能性。在这里，157个细菌与四个常见的珊瑚物种进行了分离和筛选，他们的能力，产生DMSP的目标dsyB，一个关键基因参与DMSP的生物合成。大约9%（14/157）的细菌分离株携带dsyB，均为α变形菌门的成员。通过液相色谱-质谱（LC-MS）和核磁共振（NMR）测量证实了这些分离物产生DMSP的能力。选择携带dsyB的菌株志贺氏菌AMM-P-2进行基因组测序。该菌株具有完整的遗传机制，以（i）同化硫酸盐并合成DMSP前体、半胱氨酸和甲硫氨酸;（ii）使DMSP脱甲基并产生甲硫醇;（iii）裂解DMSP，产生二甲基硫醚（DMS）和丙烯酸酯;以及（iv）利用或解毒丙烯酸酯。研究了不同环境因子（温度、盐度、光照和紫外辐射）对S. aestuariiAMM-P-2 DMSP生物合成的特征。S. Aestuarii AMM-P-2在高盐条件（40 PSU）和高UV暴露下几乎增加两倍。在这些条件下，DMSP通过裂解途径的催化剂也增加，产生抗氧化剂DMS和丙烯酸酯，这是对氧化应激产生的潜在反应。总体而言，我们的研究结果表明，珊瑚相关的细菌可以合成DMSP，因此可能有助于DMSP生产的珊瑚holobiont。
Dimethylsulfoniopropionate (DMSP) is an important molecule in the marine sulfur cycle, produced in large amounts by corals and their dinoflagellate endosymbionts, Symbiodiniaceae. Although corals are known to harbour bacteria that can catabolise DMSP, the recent discovery of bacteria capable of producing DMSP in coastal and deep-sea environments raises the possibility of a bacterial contribution to the DMSP output of corals. Here, 157 bacteria associated with four common coral species were isolated and screened for their ability to produce DMSP by targeting dsyB, a key gene involved in DMSP biosynthesis. Approximately 9% (14 out of 157) of the bacterial isolates harboured dsyB, all being members of the Alphaproteobacteria. The ability of these isolates to produce DMSP was confirmed by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) measurements. A dsyB-harbouring strain, Shimia aestuarii AMM-P-2, was selected for genome sequencing. This strain harbours the complete genetic machinery to (i) assimilate sulfate and synthesise the DMSP precursors, cysteine and methionine; (ii) demethylate DMSP and generate methanethiol; (iii) cleave DMSP, generating dimethyl sulfide (DMS) and acrylate; and (iv) utilise or detoxify acrylate. The impacts of varied environmental factors (temperature, salinity, light and UV radiation) on S. aestuarii AMM-P-2 DMSP biosynthesis were characterised. DMSP levels in S. aestuarii AMM-P-2 increased almost two-fold under both hypersaline conditions (40 PSU) and high UV exposure. DMSP catabolism through the cleavage pathway also increased under these conditions, producing the antioxidants DMS and acrylate, a potential response to the oxidative stress generated. Overall, our results reveal that coral-associated bacteria can synthesize DMSP and may therefore contribute to DMSP production by the coral holobiont.