University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, New South Wales, Australia.
School of Mathematics and Statistics, The University of Melbourne, Parkville, Victoria, Australia.
Nat Microbiol. 2023 Mar;8(3):510-521. doi: 10.1038/s41564-023-01327-9. Epub 2023 Feb 9.
Behaviours such as chemotaxis can facilitate metabolic exchanges between phytoplankton and heterotrophic bacteria, which ultimately regulate oceanic productivity and biogeochemistry. However, numerically dominant picophytoplankton have been considered too small to be detected by chemotactic bacteria, implying that cell-cell interactions might not be possible between some of the most abundant organisms in the ocean. Here we examined how bacterial behaviour influences metabolic exchanges at the single-cell level between the ubiquitous picophytoplankton Synechococcus and the heterotrophic bacterium Marinobacter adhaerens, using bacterial mutants deficient in motility and chemotaxis. Stable-isotope tracking revealed that chemotaxis increased nitrogen and carbon uptake of both partners by up to 4.4-fold. A mathematical model following thousands of cells confirmed that short periods of exposure to small but nutrient-rich microenvironments surrounding Synechococcus cells provide a considerable competitive advantage to chemotactic bacteria. These findings reveal that transient interactions mediated by chemotaxis can underpin metabolic relationships among the ocean's most abundant microorganisms.
行为，如趋化性，可以促进浮游植物和异养细菌之间的代谢交换，这最终调节海洋生产力和生物地球化学。然而，数量上占优势的微微型浮游植物被认为太小而不能被趋化细菌检测到，这意味着细胞-细胞相互作用可能不是海洋中一些最丰富的生物之间的可能。在这里，我们使用运动和趋化性缺陷的细菌突变体研究了细菌行为如何影响普遍存在的微微型浮游植物聚球藻和异养细菌海栖杆菌之间的单细胞水平的代谢交换。稳定同位素示踪表明，趋化作用使两个伙伴的氮和碳吸收增加了 4.4 倍。一个跟踪数千个细胞的数学模型证实，短暂暴露在围绕聚球藻细胞的小但富含营养的微环境中，为趋化细菌提供了相当大的竞争优势。这些发现表明，趋化作用介导的短暂相互作用可以为海洋中最丰富的微生物之间的代谢关系提供支撑。
