Stripping the molecular basis of marine microbial interactions

海洋初级生产主要是由微观浮游植物驱动的，因为光养微蓝细菌和微真核生物几乎参与了贫营养开阔海洋广阔透光区的所有光合作用。微蓝细菌、绿色藻类、硅藻和原生藻类是地球上数量最丰富的初级生产者，预计其中一些的丰度将因气候变化而增加。海洋浮游微生物通常表现出稳定的细胞数量，生长和损失基本平衡。最终，所有初级生产将转化为颗粒或溶解有机物（DOM），成为复杂的海洋食物网（主要是异养细菌）的主要碳和能量来源。DOM被认为是由细胞死亡、病毒裂解和无效放牧产生的，但已知活生物本身也是不可避免或“故意”泄漏的，例如通过产生细胞外囊泡、主动外排过程或简单地通过渗透膜泄漏。从这个意义上说，浮游植物驱动细菌群落动态，因为它们是有机物质的主要供应者。我们最近观察到，营养交换在光养-异养相互作用中起着关键作用，该小组目前的工作表明，不同的浮游植物物种产生各种代谢产物，这些代谢产物调节它们共同存在的异养细菌的反应和行为。其中，磷的重要性是显著的。最近的建模发现，磷的优先再矿化可以增加生物泵的强度和全球净初级生产，包括增加对氮等其他代谢物的利用。因此，该项目旨在剖析这些系统中产生的关键代谢物，并确定这些代谢物如何对其他物种产生影响。

Marine primary production is mainly driven by microscopic phytoplankton since phototrophic picocyanobacteria and picoeukaryotes contribute to almost all photosynthesis that takes place in the vast photic zones of the oligotrophic open ocean. Picocyanobacteria, green algae, diatoms and prymnesiophytes are the numerically most abundant primary producers on Earth and the abundance of some of them is predicted to increase due to climate change. Marine planktonic microorganisms generally show stable cell numbers, with growth and loss largely balanced. Ultimately, all primary production will be converted into particulate or dissolved organic matter (DOM) which becomes the main source of carbon and energy for the complex marine food web (mainly, heterotrophic bacteria). DOM is thought to be generated by cell death, viral lysis and inefficient grazing, but also living organisms are known to be, per se, inevitably or 'intentionally' leaky, e.g. through the production of extracellular vesicles, active efflux processes or, simply, permeable membrane leakage. In this sense, phytoplankton drive bacterial community dynamics as they are the main suppliers of organic matter. We recently observed that nutrient exchange plays a key role in phototroph-heterotroph interactions and current work in the group has shown that different phytoplankton species generate a variety of metabolites that condition the response and behaviour of their co-occurring heterotrophic bacteria. Of these, phosphorus is of notable import. Recent modelling has found preferential remineralisation of phosphorus to increase the strength of the biological pump and global net primary production in general, including increased utilisation of other metabolites such as nitrogen. Hence, this project aims to dissect the key metabolites produced in these systems and determine how these exert an influence on other species.