Biology subjects

Bannon, C. C.

Publications and source records attributed to Bannon, C. C..

5 recordsLinked to original sources

bioRxiv2026

Novel connections between B-vitamins and microbial communities along biogeochemical gradients in a large temperate estuary

As B-vitamins are organic cofactors required by prokaryotic and eukaryotic planktonic cells, their availability impacts aquatic microbial communities and associated biogeochemistry. Contrary to inorganic nutrients, measurements of B-vitamins from brackish systems are scarce and relationships between B-vitamins and plankton composition in estuaries are unclear, limiting our understanding of estuary biology in general as well as how B-vitamins are distributed and dispersed in marine systems. Here, we quantify multiple B-vitamins and their vitamers in particulate and dissolved phases, and characterize microbial community composition, across fresh to polyhaline zones of the Neuse River Estuary (NRE), North Carolina, USA. We uncover elevated concentrations of B-vitamins within the mid-estuary, Chlorophyll a maximum along with a unique suite of dissolved B-vitamin associated with sporadic surges in pico- and microplankton populations. The dynamics of both dissolved and particulate B-vitamin concentrations in space and time were striking - from subpicomolar to high picomolar levels observed and strong short-term (weeks) variability. We find notable autochtonous B-vitamin production in the estuary, but we expect the ability of the system to deliver these micronutrients to the ocean will depend on flushing as well as changes in microbial community. We identify vitamin B1, B12, psB12 (pseudocobalamin), and B3 as key explanatory variables for change in prokaryotic and eukaryotic NRE plankton, providing new evidence of B-vitamin influence upon estuarine plankton community composition. Our work reveals new complexities in B-vitamin production and consumption within zones of estuaries while underscoring these micronutrients as key drivers of microbial plankton composition.

ecology↗

bioRxiv2024

Production of the cobalamin lower ligand, 5,6-dimethylbenzimidazole, by a diatom under cobalamin-deplete conditions

Cobalamin, or vitamin B12, is a micronutrient required by half of all surveyed phytoplankton but produced only by select bacteria and archaea. Cobalamin influences community composition and primary productivity in various regions of the ocean and has been shown to be a critical currency in microbial interactions. Many marine microorganisms can salvage cobinamide and remodel pseudocobalamin, to generate cobalamin using the lower ligand 5,6-dimethylbenzimidazole (DMB), or the ribosylated form, -ribazole. The sources of the cobalamin lower ligand and intermediate remain poorly characterized but are currently attributed to prokaryotes alone. Here, we grew axenic cultures of a recently isolated Thalassiosiraceae diatom over a range of cobalamin concentrations (0, 0.75, 10, 100 pM). Then, using mass spectrometry, we quantified cobalamin and -ribazole in both particulate (cellular) and dissolved (media) phases. We found that this diatom is a facultative cobalamin consumer: it takes up cobalamin when available but can survive in its absence. Strikingly, under low cobalamin availability, we demonstrate that the diatom produces -ribazole. This highlights eukaryotic production as a source of the molecule and suggests that salvaging and remodeling by phytoplankton may be less dependent on prokaryotes than previously imagined. We detected -ribazole in the spent media during stationary phase, highlighting eukaryotic production of the molecule as a public good. We provide evidence that -ribazole is produced by this diatom as a mechanism to cope with low cobalamin availability, suggesting that even amongst organisms that dont absolutely require it, cobalamin use has important consequences for fitness. Importance SectionCobalamin (vitamin B12) is a scarce micronutrient in the ocean that impacts the composition and activity of marine microbial communities. Microbes employ a range of strategies to cope with low cobalamin availability, including remodeling cobalamin intermediates and alternatives into cobalamin when the lower ligand is available. Here we show that a recently isolated Thalassiosiraceae diatom doesnt need cobalamin to survive but will take it up and use it when available. Additionally, the diatom produces the lower ligand (-ribazole) under low cobalamin conditions. The production of -ribazole was previously thought to be restricted to bacteria and archaea, so these results suggest that eukaryotes could play a larger role in cobamide remodeling than previously imagined. This work also demonstrates that even organisms that dont absolutely require cobalamin for survival have adopted metabolic strategies to cope with its absence, emphasizing the importance of this vitamin for phytoplankton metabolism.

microbiology↗

bioRxiv2024

Seasonal patterns in b-vitamins and cobalamin co-limitation in the Northwest Atlantic

B-vitamins are important co-enzymes that have long been hypothesized to play key roles in marine ecosystems. However, environmental measurements remain scarce, which limits our understanding of their potential impact. Here, we present mass spectrometry-based measurements of b-vitamins (B1, B2, B3, B5, B6, B12) and related vitamers along a transect in the Northwest Atlantic Ocean, in both particulate phase and dissolved in seawater, seasonally over 5 years, and couple this with targeted investigations of the impact of B12 (cobalamin) on phytoplankton growth. We show that these metabolites are present at femto to pico-molar concentrations and demonstrate that season explains most variance in particulate phase b-vitamins but not dissolved, offering further evidence that metabolite inventories in these two phases are often decoupled. We find correlations between particulate organic carbon with particulate B1 and B3, and between chlorophyll a and particulate B2 and DMB in fall but not spring, indicating unique seasonal drivers of vitamin inventories. Of all measured vitamins, only cobalamin was enriched in the particulate over dissolved phase, predominantly in spring. We documented nitrogen and cobalamin co-limitation of phytoplankton growth during spring bloom decline, when dissolved cobalamin is seemingly drawn down, but not during fall, when dissolved cobalamin concentrations remain elevated. These seasonal differences may be underpinned by the increased importance of cobalamin remodeling and recycling during the fall. This study provides insights into the absolute concentrations, stoichiometry, and variability of b-vitamins in the ocean and offers evidence that cobalamin exerts seasonally-varying controls on Northwest Atlantic marine ecosystems.

microbiology↗

bioRxiv2024

Pseudocobalamin production and use in Synechococcus cultures and communities

Cobalamin influences marine microbial communities because an exogenous source is required by most eukaryotic phytoplankton, and demand can exceed supply. Pseudocobalamin is a cobalamin analog that is produced and used by most cyanobacteria but is not directly available to eukaryotic phytoplankton. Some microbes can remodel pseudocobalamin into cobalamin, but a scarcity of pseudocobalamin measurements impedes our ability to evaluate its importance for marine cobalamin production. Here, we perform simultaneous measurements of pseudocobalamin and methionine synthase (MetH), the key protein that uses it as a co-factor, in Synechococcus cultures and communities. In Synechococcus sp. WH8102, pseudocobalamin quota decreases in low temperature (17 {degrees}C) and low N:P, while MetH did not. Pseudocobalamin and MetH quotas were influenced by culture methods and growth phase. Despite the variability present in cultures, we found a comparably consistent quota of 300 {+/-} 100 pseudocobalamin molecules per cyanobacterial cell in the Northwest Atlantic Ocean, suggesting that cyanobacterial cell counts may be sufficient to estimate pseudocobalamin inventories in this region. This work offers insights into cellular pseudocobalamin metabolism, and the environmental and physiological conditions that may influence it, and provides environmental measurements to further our understanding of when and how pseudocobalamin can influence marine microbial communities.

microbiology↗

bioRxiv2021

Global Metabolome Analysis of Dunaliella tertiolecta, Phaeobacter italicus R11 Co-cultures using Thermal Desoprtion - Comprehensive Two-dimensional Gas Chromatography - Time-of-Flight Mass Spectrometry

Dunaliella tertiolecta is a marine microalgae that has been studied extensively as a potential carbon-neutral biofuel source [1]. Microalgae oil contains high quantities of energy-rich fatty acids and lipids, but is not yet commercially viable as an alternative fuel. Carefully optimised growth conditions, and more recently, algal-bacterial co-cultures have been explored as a way of improving the yield of Dunaliella tertiolecta microalgae oils. The relationship between the host microalgae and bacterial co-cultures is currently poorly understood. Here, a complete workflow is proposed to analyse the global metabolomic profile of co-cultured Dunaliella tertiolectra and Phaeobacter italicus R11, which will enable researchers to explore the chemical nature of this relationship in more detail. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/461748v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@18c3cb0org.highwire.dtl.DTLVardef@1e48735org.highwire.dtl.DTLVardef@68a98borg.highwire.dtl.DTLVardef@15306bc_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIA method for direct microalgae sample introduction is proposed. C_LIO_LIAdvanced chemometric tools can extract, useful and discriminating metabolomic features even from very noisy complex datasets. C_LI

plant biology↗