MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany.
Department of Earth Sciences, Utrecht University, Utrecht, Netherlands.
Sci Adv. 2024 May 17;10(20):eadm8096. doi: 10.1126/sciadv.adm8096.
Organic matter (OM) transformations in marine sediments play a crucial role in the global carbon cycle. However, secondary production and priming have been ignored in marine biogeochemistry. By incubating shelf sediments with various C-labeled algal substrates for 400 days, we show that ~65% of the lipids and ~20% of the proteins were mineralized by numerically minor heterotrophic bacteria as revealed by RNA stable isotope probing. Up to 11% of carbon from the algal lipids was transformed into the biomass of secondary producers as indicated by C incorporation in amino acids. This biomass turned over throughout the experiment, corresponding to dynamic microbial shifts. Algal lipid addition accelerated indigenous OM degradation by 2.5 to 6 times. This priming was driven by diverse heterotrophic bacteria and sulfur- and iron-cycling bacteria and, in turn, resulted in extra secondary production, which exceeded that stimulated by added substrates. These interactions between degradation, secondary production, and priming govern the eventual fate of OM in marine sediments.
海洋沉积物中的有机物质（OM）转化在全球碳循环中起着至关重要的作用。然而，海洋生物地球化学中一直忽略了次生生产和激发作用。通过用各种 C 标记的藻类底物孵育大陆架沉积物 400 天，我们表明，数值上较少的异养细菌矿化了约 65%的脂质和约 20%的蛋白质，这是通过 RNA 稳定同位素探测揭示的。如氨基酸中的 C 掺入所示，藻类脂质中高达 11%的碳被转化为次生生产者的生物量。整个实验过程中，这种生物量都在不断转化，对应着动态的微生物变化。藻类脂质的添加将土著 OM 降解加速了 2.5 到 6 倍。这种激发作用是由多种异养细菌、硫和铁循环细菌驱动的，反过来又导致了额外的次生生产，超过了添加底物所刺激的生产。这些降解、次生生产和激发作用之间的相互作用决定了海洋沉积物中 OM 的最终命运。
