RAS-METAG-SO. Southern Ocean Metagenomes (RAS)

The Southern Ocean is the largest High Nutrient Low Chlorophyll (HNLC) area where major nutrients are perennially present at high concentrations yet phytoplankton biomass remains low. Surface depletion in iron (Fe) was demonstrated to be the cause of an inefficient biological pump of carbon in the Southern Ocean. While the effect of Fe on phytoplankton has been investigated in detail, it is not well understood how this and potentially other trace metals affect heterotrophic microbial metabolism. Fe and carbon are tightly coupled in a suite of metabolic processes crucial for growth. Fe plays a pivotal role in the carbon metabolism, in particular because processes related to respiration rely on multiple Fe-containing enzymes. A deficiency in Fe ultimately results in a reduction in the metabolic activity and the transformation of organic carbon. These observations raise the question of the mechanisms used by microbial taxa to acquire and metabolize Fe and organic carbon in cellular processes. The main objectives of this project is to study the temporal and spatial variability of physiological strategies of heterotrophic microbes to utilize iron and organic carbon.

南大洋是全球最大的高营养盐低叶绿素（High Nutrient Low Chlorophyll, HNLC）海域，该区域常年维持高浓度的主要营养盐，但浮游植物生物量却始终处于较低水平。研究证实，南大洋中铁（Fe）的表层耗竭是导致其碳生物泵效率低下的核心原因。尽管学界已针对铁对浮游植物的影响开展了详尽研究，但对于铁及其他潜在痕量金属如何影响异养微生物代谢的机制，目前仍缺乏清晰认知。铁与碳在一系列对微生物生长至关重要的代谢过程中存在紧密耦合关系，铁在碳代谢过程中发挥关键作用，尤其是呼吸相关的代谢过程依赖多种含铁酶类。铁缺乏最终会导致微生物代谢活性下降，并改变有机碳的转化过程。上述研究空白引出了核心科学问题：微生物类群在细胞过程中获取并代谢铁与有机碳的具体机制是什么。本项目的核心研究目标为解析异养微生物利用铁与有机碳的生理策略的时空变异规律。