Bioorganic Analytics, Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Lessingstrasse 8, D-07743 Jena, Germany.
MPG Fellow Group, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745 Jena, Germany.
Mar Drugs. 2021 Nov 30;19(12):683. doi: 10.3390/md19120683.
Phytoplankton rely on bioactive zwitterionic and highly polar small metabolites with osmoregulatory properties to compensate changes in the salinity of the surrounding seawater. Dimethylsulfoniopropionate (DMSP) is a main representative of this class of metabolites. Salinity-dependent DMSP biosynthesis and turnover contribute significantly to the global sulfur cycle. Using advanced chromatographic and mass spectrometric techniques that enable the detection of highly polar metabolites, we identified cysteinolic acid as an additional widely distributed polar metabolite in phytoplankton. Cysteinolic acid belongs to the class of marine sulfonates, metabolites that are commonly produced by algae and consumed by bacteria. It was detected in all dinoflagellates, haptophytes, diatoms and prymnesiophytes that were surveyed. We quantified the metabolite in different phytoplankton taxa and revealed that the cellular content can reach even higher concentrations than the ubiquitous DMSP. The cysteinolic acid concentration in the cells of the diatom increases significantly when grown in a medium with elevated salinity. In contrast to the compatible solute ectoine, cysteinolic acid is also found in high concentrations in axenic algae, indicating biosynthesis by the algae and not the associated bacteria. Therefore, we add this metabolite to the family of highly polar metabolites with osmoregulatory characteristics produced by phytoplankton.
浮游植物依赖具有渗透调节特性的生物活性两性离子和高度极性的小分子代谢物来补偿周围海水盐度的变化。二甲亚砜（DMSP）是此类代谢物的主要代表。盐度依赖性 DMSP 生物合成和周转对全球硫循环有重要贡献。使用能够检测高度极性代谢物的先进色谱和质谱技术，我们确定半胱氨酸酸是浮游植物中另一种广泛分布的极性代谢物。半胱氨酸酸属于海洋磺酸盐类，是藻类普遍产生、细菌消耗的代谢物。在所调查的所有甲藻、甲藻、硅藻和金藻中都检测到了这种酸。我们定量了不同浮游植物类群中的代谢物，并发现其细胞含量甚至可以达到比普遍存在的 DMSP 更高的浓度。在高盐度培养基中生长时，硅藻细胞中的半胱氨酸酸浓度显著增加。与相容性溶质海藻糖不同，半胱氨酸酸在无菌藻类中也以高浓度存在，表明其由藻类而不是相关细菌合成。因此，我们将这种代谢物添加到具有渗透调节特性的高度极性代谢物家族中，这些代谢物由浮游植物产生。
