The outbreak of Ulva prolifera blooms causes significant changes in the coastal sulfur cycle due to the high production of dimethylsulfoniopropionate (DMSP) and the emission of dimethylsulfide (DMS). However, the sulfur metabolism mechanism of U. prolifera has not been thoroughly investigated. In this study, we examined the levels of intracellular and extracellular sulfate (SO₄²⁻-S), total sulfur (TS), DMSP, and DMS in fresh U. prolifera under different light intensity conditions (54, 108 and 162 μmol photons m^–2 s^–1) during algal growth. We also conducted transcriptome analyses to investigate sulfur uptake and metabolism. When the light intensity increased by 50% (from 108 to 162 μmol photons m^–2 s^–1), the amount of absorbed SO₄²⁻-S increased by 3.5 times after 24 hours, while the fresh weight of U. prolifera increased by 16%, and the average release rates of DMS and DMSP increased by 136% and 100%, respectively. However, the expression of sulfate transporter and assimilation-related genes did not show significant up- or down-regulation in response to the light intensity changes. Therefore, it is speculated that the key gene responsible for DMSP synthesis in U. prolifera has not yet been identified. The sulfate metabolic pathway of U. prolifera was established, and four Alma genes, including DMSP lyase, were identified. During the bloom period, it is estimated that U. prolifera releases a maximum of approximately 0.4 tons of sulfur and 0.3 tons of carbon in the form of DMS into the atmosphere per day. Additionally, biogenic sulfur dissolved in seawater or within algae could potentially impact the regional climate and environment.

中文翻译：

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石莼增殖绿潮中的硫代谢和对光的反应


由于二甲基磺酰丙酸酯 （DMSP） 的高产量和二甲基硫醚 （DMS） 的排放，石莼增殖水华的爆发导致沿海硫循环发生重大变化。然而，U. prolifera 的硫代谢机制尚未得到彻底研究。在这项研究中，我们检查了藻类生长过程中不同光照强度条件下 （54、108 和 162 μmol 光子 m ^–2 s ^–1 ） 新鲜 U . prolifera 中细胞内和细胞外硫酸盐 （SO ₄ ²⁻ -S） 、总硫 （TS） 、DMSP 和 DMS 的水平。我们还进行了转录组分析以研究硫的摄取和代谢。当光强度增加 50% （从 108 μmol 光子 m s 增加到 162 μmol 光子 m ^–2 s ^–1 ） 时，吸收的 SO ₄ ²⁻ -S 量在 24 h 后增加了 3.5 倍，而 U. prolifera 的鲜重增加了 16%，DMS 和 DMSP 的平均释放速率分别增加了 136% 和 100%。然而，硫酸盐转运蛋白和同化相关基因的表达在响应光强度变化时没有表现出显着的上调或下调。因此，推测 U. prolifera 中负责 DMSP 合成的关键基因尚未确定。建立了 U. prolifera 的硫酸盐代谢途径，并鉴定了包括 DMSP 裂解酶在内的 4 个 Alma 基因。在水华期间，据估计，U. prolifera 每天最多以 DMS 的形式向大气中释放约 0.4 吨硫和 0.3 吨碳。此外，溶解在海水或藻类中的生物硫可能会影响区域气候和环境。