The communities of bacteria that assemble around marine microphytoplankton are predictably dominated by Rhodobacterales, Flavobacteriales, and families within the Gammaproteobacteria. Yet whether this consistent ecological pattern reflects the result of resource-based niche partitioning or resource competition requires better knowledge of the metabolites linking microbial autotrophs and heterotrophs in the surface ocean. We characterized molecules targeted for uptake by three heterotrophic bacteria individually co-cultured with a marine diatom using two strategies that vetted the exometabolite pool for biological relevance by means of bacterial activity assays: expression of diagnostic genes and net drawdown of exometabolites, the latter detected with mass spectrometry and nuclear magnetic resonance using novel sample preparation approaches. Of the more than 36 organic molecules with evidence of bacterial uptake, 53% contained nitrogen (including nucleosides and amino acids), 11% were organic sulfur compounds (including dihydroxypropanesulfonate and dimethysulfoniopropionate), and 28% were components of polysaccharides (including chrysolaminarin, chitin, and alginate). Overlap in phytoplankton-derived metabolite use by bacteria in the absence of competition was low, and only guanosine, proline, and N-acetyl-d-glucosamine were predicted to be used by all three. Exometabolite uptake pattern points to a key role for ecological resource partitioning in the assembly marine bacterial communities transforming recent photosynthate.

可以预见，在海洋微型浮游植物周围聚集的细菌群落主要由红杆菌目、黄杆菌目和 Gammaproteobacteria 中的科组成。然而，这种一致的生态模式是否反映了基于资源的生态位划分或资源竞争的结果，需要更好地了解连接表层海洋中微生物自养生物和异养生物的代谢物。我们使用两种策略对三种异养细菌分别与海洋硅藻共培养的目标进行了表征，这些策略通过细菌活性测定来审查外代谢物库的生物学相关性：诊断基因的表达和外代谢物的净下降，后者检测到质谱和核磁共振使用新的样品制备方法。在超过 36 个有细菌吸收证据的有机分子中，53% 含有氮（包括核苷和氨基酸），11% 是有机硫化合物（包括二羟基丙磺酸盐和二甲基磺基丙酸盐），28% 是多糖成分（包括菊碱、几丁质） , 和藻酸盐)。在没有竞争的情况下，细菌使用浮游植物衍生代谢物的重叠率很低，只有鸟苷、脯氨酸和预计这三个人都会使用N-乙酰基-d-葡糖胺。外代谢物吸收模式指出了生态资源分配在海洋细菌群落中转化近期光合产物的关键作用。