Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA.
Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
Nat Commun. 2023 Sep 13;14(1):5642. doi: 10.1038/s41467-023-41179-9.
Bacterial remineralization of algal organic matter fuels algal growth but is rarely quantified. Consequently, we cannot currently predict whether some bacterial taxa may provide more remineralized nutrients to algae than others. Here, we quantified bacterial incorporation of algal-derived complex dissolved organic carbon and nitrogen and algal incorporation of remineralized carbon and nitrogen in fifteen bacterial co-cultures growing with the diatom Phaeodactylum tricornutum at the single-cell level using isotope tracing and nanoSIMS. We found unexpected strain-to-strain and cell-to-cell variability in net carbon and nitrogen incorporation, including non-ubiquitous complex organic nitrogen utilization and remineralization. We used these data to identify three distinct functional guilds of metabolic interactions, which we termed macromolecule remineralizers, macromolecule users, and small-molecule users, the latter exhibiting efficient growth under low carbon availability. The functional guilds were not linked to phylogeny and could not be elucidated strictly from metabolic capacity as predicted by comparative genomics, highlighting the need for direct activity-based measurements in ecological studies of microbial metabolic interactions.
藻类有机物的细菌再矿化为藻类生长提供了燃料，但这种作用很少被量化。因此，我们目前无法预测某些细菌类群是否比其他细菌类群为藻类提供更多的可再矿化营养物质。在这里，我们使用同位素示踪和纳米二次离子质谱法，在单细胞水平上，在十五个与硅藻角毛藻共培养的细菌共培养物中，量化了细菌对藻类来源的复杂溶解有机碳和氮的摄取以及对再矿化碳和氮的摄取。我们发现，净碳和氮摄取的菌株间和细胞间存在意外的变异性，包括普遍存在的复杂有机氮利用和再矿化。我们利用这些数据确定了三种不同的代谢相互作用功能群，我们称之为大分子再矿化剂、大分子利用者和小分子利用者，后者在低碳可用性下表现出高效生长。功能群与系统发育无关，也不能仅从比较基因组学预测的代谢能力来阐明，这突出了在微生物代谢相互作用的生态研究中直接进行基于活性的测量的必要性。
