State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, People's Republic of China.
Appl Environ Microbiol. 2011 Nov;77(21):7439-44. doi: 10.1128/AEM.05640-11. Epub 2011 Aug 26.
The majority of marine dissolved organic carbon (DOC) is resistant to biological degradation and thus can remain in the water column for thousands of years, constituting carbon sequestration in the ocean. To date the origin of such recalcitrant DOC (RDOC) is unclear. A recently proposed conceptual framework, the microbial carbon pump (MCP), emphasizes the microbial transformation of organic carbon from labile to recalcitrant states. The MCP is concerned with both microbial uptakes and outputs of DOC compounds, covering a wide range from gene to ecosystem levels. In this minireview, the ATP binding cassette (ABC) transporter is used as an example for the microbial processing of DOC at the genetic level. The compositions of the ABC transporter genes of the two major marine bacterial clades Roseobacter and SAR11 demonstrate that they have distinct patterns in DOC utilization: Roseobacter strains have the advantage of taking up carbohydrate DOC, while SAR11 bacteria prefer nitrogen-containing DOC. At the ecosystem level, bacterially derived RDOC based on d-amino acid biomarkers is reported to be responsible for about a quarter of the total marine RDOC pool. Under future global warming scenarios, partitioning of primary production into DOC could be enhanced, and thus the MCP could play an even more important role in carbon sequestration by the ocean. Joint efforts to study the MCP from multiple disciplines are required to obtain a better understanding of ocean carbon cycle and its coupling with global change.
海洋溶解有机碳（DOC）的大部分对生物降解具有抗性，因此可以在水柱中停留数千年，从而构成海洋中的碳封存。迄今为止，这种顽固的 DOC（RDOC）的起源尚不清楚。最近提出的一个概念框架，微生物碳泵（MCP），强调了有机碳从易降解状态向难降解状态的微生物转化。MCP 涉及到 DOC 化合物的微生物摄取和输出，涵盖了从基因到生态系统水平的广泛范围。在这篇小综述中，ATP 结合盒（ABC）转运蛋白被用作微生物在遗传水平上处理 DOC 的一个例子。两个主要海洋细菌类群玫瑰杆菌和 SAR11 的 ABC 转运蛋白基因的组成表明，它们在 DOC 利用方面具有不同的模式：玫瑰杆菌菌株具有摄取碳水化合物 DOC 的优势，而 SAR11 细菌则更喜欢含氮的 DOC。在生态系统水平上，基于 D-氨基酸生物标志物的细菌衍生的 RDOC 据报道占海洋总 RDOC 库的四分之一左右。在未来的全球变暖情景下，初级生产力向 DOC 的分配可能会增强，因此 MCP 在海洋碳封存中可能会发挥更重要的作用。需要多学科联合研究 MCP，以更好地了解海洋碳循环及其与全球变化的耦合。
