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Abstract Organic carbon transfer between surface ocean photosynthetic and heterotrophic microbes is a central but poorly understood process in the global carbon cycle. In a model community in which diatom extracellular release of organic molecules sustained growth of a co-cultured bacterium, we determined quantitative changes in the diatom endometabolome and the bacterial uptake transcriptome over two diel cycles. Of the nuclear magnetic resonance (NMR) peaks in the diatom endometabolites, 38% had diel patterns with noon or mid-afternoon maxima; the remaining either increased (36%) or decreased (26%) through time. Of the genes in the bacterial uptake transcriptome, 94% had a diel pattern with a noon maximum; the remaining decreased over time (6%). Eight diatom endometabolites identified with high confidence were matched to the bacterial genes mediating their utilization. Modeling of these coupled inventories with only diffusion-based phytoplankton extracellular release could not reproduce all the patterns. Addition of active release mechanisms for physiological balance and bacterial recognition significantly improved model performance. Estimates of phytoplankton extracellular release range from only a few percent to nearly half of annual net primary production. Improved understanding of the factors that influence metabolite release and consumption by surface ocean microbes will better constrain this globally significant carbon flux.
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This content will become publicly available on August 1, 2026
Using the diel cycle of ocean microbes to better understand their biogeochemical functions
Abstract The daily cycle of solar radiation has a profound influence in structuring the physiology of microbes in the euphotic zone and subsequently setting the degree of coupling across trophic levels within ocean ecosystems. There has been an upsurge of interest in the biological role of the diel cycle and the ability to probe it using molecular approaches (i.e., “omics”), which now allow us to pinpoint the level of detail of the diel cycle that is required to better understand microbes' roles across multiple biogeochemical cycles. Although sampling the diel cycle requires additional resources, the payback is large. A better understanding of the diel cycle provides a holistic framework with which to align patterns and causal sequences across multi‐omic layers, yielding consequent connections with metabolic processes to develop more robust mechanistic models. Such models provide the stepping stones to better understand how resource allocation in cells is driven by environmental forcing.
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- Award ID(s):
- 2022597
- PAR ID:
- 10658749
- Publisher / Repository:
- Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.
- Date Published:
- Journal Name:
- Limnology and Oceanography Letters
- Volume:
- 10
- Issue:
- 4
- ISSN:
- 2378-2242
- Page Range / eLocation ID:
- 434 to 447
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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