Max Planck Institute for Marine Microbiology, Bremen, Germany.
Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands.
Nat Commun. 2023 Feb 20;14(1):938. doi: 10.1038/s41467-023-35818-4.
Intertidal permeable sediments are crucial sites of organic matter remineralization. These sediments likely have a large capacity to produce reactive oxygen species (ROS) because of shifting oxic-anoxic interfaces and intense iron-sulfur cycling. Here, we show that high concentrations of the ROS hydrogen peroxide are present in intertidal sediments using microsensors, and chemiluminescent analysis on extracted porewater. We furthermore investigate the effect of ROS on potential rates of microbial degradation processes in intertidal surface sediments after transient oxygenation, using slurries that transitioned from oxic to anoxic conditions. Enzymatic removal of ROS strongly increases rates of aerobic respiration, sulfate reduction and hydrogen accumulation. We conclude that ROS are formed in sediments, and subsequently moderate microbial mineralization process rates. Although sulfate reduction is completely inhibited in the oxic period, it resumes immediately upon anoxia. This study demonstrates the strong effects of ROS and transient oxygenation on the biogeochemistry of intertidal sediments.
潮间带可渗透沉积物是有机质再矿化的关键场所。由于氧-缺氧界面的变化和强烈的铁-硫循环，这些沉积物可能具有产生活性氧物质 (ROS) 的巨大能力。在这里，我们使用微传感器和提取的孔隙水中的化学发光分析表明，ROS 过氧化氢在潮间带沉积物中存在高浓度。我们进一步研究了 ROS 对潮间带表层沉积物中微生物降解过程潜在速率的影响，这些沉积物在短暂的氧气供应后，从好氧条件过渡到缺氧条件。ROS 的酶促去除强烈增加了好氧呼吸、硫酸盐还原和氢气积累的速率。我们得出结论，ROS 在沉积物中形成，并随后调节微生物矿化过程的速率。虽然硫酸盐还原在好氧期完全受到抑制，但在缺氧期立即恢复。这项研究表明，ROS 和短暂氧气供应对潮间带沉积物生物地球化学的强烈影响。
