Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstrasse 15, 04318, Leipzig, Germany.
Department of Earth System Science, Stanford University, Green Earth Sciences Building, 367 Panama St., Room 129, Stanford, CA, 94305-4216, USA.
Sci Rep. 2022 Sep 2;12(1):14949. doi: 10.1038/s41598-022-18915-0.
Bacterial degradation of sinking diatom aggregates is key for the availability of organic matter in the deep-ocean. Yet, little is known about the impact of aggregate colonization by different bacterial taxa on organic carbon and nutrient cycling within aggregates. Here, we tracked the carbon (C) and nitrogen (N) transfer from the diatom Leptocylindrus danicus to different environmental bacterial groups using a combination of C and N isotope incubation (incubated for 72 h), CARD-FISH and nanoSIMS single-cell analysis. Pseudoalteromonas bacterial group was the first colonizing diatom-aggregates, succeeded by the Alteromonas group. Within aggregates, diatom-attached bacteria were considerably more enriched in C and N than non-attached bacteria. Isotopic mass balance budget indicates that both groups showed comparable levels of diatom C in their biomass, accounting for 19 ± 7% and 15 ± 11%, respectively. In contrast to C, bacteria of the Alteromonas groups showed significantly higher levels of N derived from diatoms (77 ± 28%) than Pseudoalteromonas (47 ± 17%), suggesting a competitive advantage for Alteromonas in the N-limiting environments of the deep-sea. Our results imply that bacterial succession within diatom aggregates may largely impact taxa-specific C and N uptake, which may have important consequences for the quantity and quality of organic matter exported to the deep ocean.
下沉硅藻聚集体的细菌降解是深海中有机物质可用性的关键。然而，对于不同细菌类群对聚集体中有机碳和营养循环的影响，我们知之甚少。在这里，我们使用 C 和 N 同位素培养（培养 72 小时）、CARD-FISH 和 nanoSIMS 单细胞分析的组合，追踪了从硅藻 Leptocylindrus danicus 到不同环境细菌群的碳（C）和氮（N）转移。假交替单胞菌细菌群是最早定植硅藻聚集体的细菌群，其次是交替单胞菌群。在聚集体内，附着在硅藻上的细菌的 C 和 N 比非附着细菌丰富得多。同位素质量平衡预算表明，这两个群体在其生物量中显示出可比水平的硅藻 C，分别为 19±7%和 15±11%。与 C 不同的是，交替单胞菌群体从硅藻中获得的 N 水平明显更高（77±28%），而假交替单胞菌（47±17%），这表明在深海 N 限制环境中，交替单胞菌具有竞争优势。我们的结果表明，硅藻聚集体内的细菌演替可能在很大程度上影响特定类群的 C 和 N 吸收，这可能对输送到深海的有机物质的数量和质量产生重要影响。
