Department of Marine Sciences, University of Georgia, Athens, Georgia, USA.
School of Oceanography, University of Washington, Seattle, Washington, USA.
Environ Microbiol Rep. 2024 Jun;16(3):e13285. doi: 10.1111/1758-2229.13285.
Marine biogeochemical cycles are built on interactions between surface ocean microbes, particularly those connecting phytoplankton primary producers to heterotrophic bacteria. Details of these associations are not well understood, especially in the case of direct influences of bacteria on phytoplankton physiology. Here we catalogue how the presence of three marine bacteria (Ruegeria pomeroyi DSS-3, Stenotrophomonas sp. SKA14 and Polaribacter dokdonensis MED152) individually and uniquely impact gene expression of the picoeukaryotic alga Micromonas commoda RCC 299. We find a dramatic transcriptomic remodelling by M. commoda after 8 h in co-culture, followed by an increase in cell numbers by 56 h compared with the axenic cultures. Some aspects of the algal transcriptomic response are conserved across all three bacterial co-cultures, including an unexpected reduction in relative expression of photosynthesis and carbon fixation pathways. Expression differences restricted to a single bacterium are also observed, with the Flavobacteriia P. dokdonensis uniquely eliciting changes in relative expression of algal genes involved in biotin biosynthesis and the acquisition and assimilation of nitrogen. This study reveals that M. commoda has rapid and extensive responses to heterotrophic bacteria in ways that are generalizable, as well as in a taxon specific manner, with implications for the diversity of phytoplankton-bacteria interactions ongoing in the surface ocean.
海洋生物地球化学循环是建立在海洋微生物相互作用的基础上的，特别是那些连接浮游植物初级生产者和异养细菌的相互作用。这些关联的细节还没有被很好地理解，特别是在细菌对浮游植物生理学的直接影响方面。在这里，我们列出了三种海洋细菌（Ruegeria pomeroyi DSS-3、 Stenotrophomonas sp. SKA14 和 Polaribacter dokdonensis MED152）单独和独特地影响微小真核藻类 Micromonas commoda RCC 299 基因表达的方式。我们发现，在共培养 8 小时后，M. commoda 的转录组发生了剧烈的重塑，随后在 56 小时内与无菌培养相比，细胞数量增加了 56 倍。藻类转录组反应的某些方面在所有三种细菌共培养中都是保守的，包括光合作用和碳固定途径的相对表达的意外降低。仅在单个细菌中观察到表达差异，Flavobacteriia P. dokdonensis 独特地引起与生物素生物合成以及氮的获取和同化相关的藻类基因相对表达的变化。这项研究表明，M. commoda 对异养细菌有快速而广泛的反应，这种反应方式是普遍存在的，同时也是以特定分类群的方式存在的，这对正在进行的海洋表面浮游植物-细菌相互作用的多样性具有重要意义。
