The balance between photosynthesis and respiration explains the niche differentiation between Crocosphaera and Cyanothece

Masuda, Takako; Inomura, Keisuke; Gao, Meng; Armin, Gabrielle; Kotabová, Eva; Bernát, Gábor; Lawrenz-Kendrick, Evelyn; Lukeš, Martin; Bečková, Martina; Steinbach, Gábor; Komenda, Josef; Prášil, Ondřej

doi:10.1016/j.csbj.2022.11.029

Cited by 7 publications

(4 citation statements)

References 46 publications

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“…The cyanobacterial diazotrophs are typically not present below the euphotic zone, with an exception of Crocosphaera (a free‐living unicellular cyanobacterial diazotroph group B, UCYN‐B) and Cyanothece (UCYN‐C), that fixes N 2 in the absence of light or in the night period (Masuda et al., 2023; Mohr et al., 2010; Wilson et al., 2017). In the Arabian Sea, unicellular cyanobacterial diazotrophs are restricted to the southern part (between 0 and 7°N) and in the upper 50 m column due to their preferential existence in warm (>29°C) and oligotrophic waters (Mazard et al., 2004).…”

Section: Discussionmentioning

confidence: 99%

“…The cyanobacterial diazotrophs are typically not present below the euphotic zone, with an exception of Crocosphaera (a free-living unicellular cyanobacterial diazotroph group B, UCYN-B) and Cyanothece (UCYN-C), that fixes N 2 in the absence of light or in the night period (Masuda et al, 2023;Mohr et al, 2010;Wilson et al, 2017).…”

Section: Active Non-cyanobacterial Diazotrophy In the Arabian Seamentioning

confidence: 99%

“…Many of the diazotrophs belong to cyanobacterial lineages fixing N 2 primarily in the light (excluding Crocosphaera and Cyanothece , Masuda et al., 2023), with light/photosynthesis alleviating the high energetic cost of N 2 fixation (Landa et al., 2021; LaRoche & Breitbarth, 2005; Lu et al., 2018). In contrast, the non‐cyanobacterial diazotrophs (NCDs) are not constrained by light (excluding photoheterotrophic NCDs), and thus, they are capable of fixing N 2 in the absence of light (Riemann et al., 2010; Zehr & Capone, 2020; Zehr et al., 1998).…”

Section: Introductionmentioning

confidence: 99%

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Winter Convective Mixing Mediating Coupling of N‐Gain and ‐Loss in the Arabian Sea

Saxena,

Sahoo,

Nazirahmed

et al. 2024

JGR Oceans

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Marine dinitrogen (N2) fixation fuels primary production and thereby influences the Earth's climate. Yet, its geographical distribution and controlling environmental parameters remain debatable. We measured N2 fixation rates from the two spatially and physicochemically contrasting regions of the Arabian Sea during the winter monsoon: (a) the colder and nutrient‐rich waters in the northern region owing to winter convection and (b) the warmer and nutrient‐poor waters in the southern region unaffected by winter convection. We found higher N2 fixation rates at the surface of northern region due to convective mixing driven supply of phosphate (intuitively iron also) from the underlying suboxic waters. N2 fixation was favored by high nutrient concentrations in the euphotic waters, whereas remained unaffected by nutrient availability in the aphotic waters. We conclude that diazotrophs dwelling in the euphotic zone chose phosphate over fixed nitrogen‐poor waters. However, we found that among oligotrophic waters, anticyclonic eddy extremes the barrier of fixed nitrogen supply, and thereby, elevates N2 fixation. While the Arabian Sea loses about 20%–40% of the global ocean fixed nitrogen, we estimate that N2 fixation in the Arabian Sea offsets only up to 42% of its fixed nitrogen‐loss by denitrification, but this offset could be higher if diazotrophic activity is further examined up to the deeper depths of the Arabian Sea.

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Section: Discussionmentioning

confidence: 99%

Section: Active Non-cyanobacterial Diazotrophy In the Arabian Seamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Winter Convective Mixing Mediating Coupling of N‐Gain and ‐Loss in the Arabian Sea

Saxena,

Sahoo,

Nazirahmed

et al. 2024

JGR Oceans

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“…Under 12h LD and diazotrophic growth conditions, the endogenous rhythm in growth coincides with the imposed LD cycles, with OD increasing for the rst 12h of light followed by decrease in OD for the subsequent 12h of darkness. This decrease in OD during the dark phase re ects carbohydrate degradation and utilization during nitrogen xation 34 . The mutant exhibited a similar diurnal rhythm in growth pattern as the WT although the growth rate and biomass accumulation were reduced (Fig.…”

Section: The ∆Kaia Mutant Exhibits Various Phenotypic Defectsmentioning

confidence: 97%

KaiA regulates intracellular oxygen dynamics in unicellular diazotrophic cyanobacteria

Bandyopadhyay

Sengupta

Pakrasi

2023

Preprint

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The discovery of nitrogen fixation in unicellular cyanobacteria provided the first clues for the existence of a circadian clock in prokaryotes. However, recalcitrance to genetic manipulation barred their use as model systems for deciphering the clock function. Here, we explore the circadian clock in the now genetically amenable Cyanothece 51142, a unicellular, nitrogen-fixing cyanobacterium. Unlike non-diazotrophic clock models, Cyanothece 51142 exhibits conspicuous self-sustained rhythms in various discernable phenotypes, offering a platform to directly study the effects of the clock on the physiology of an organism. Deletion of kaiA in this strain impacted regulation of oxygen cycling and hindered nitrogenase activity. Our findings imply a role for KaiA in regulating the intracellular oxygen dynamics in unicellular diazotrophic cyanobacteria and suggest that its addition to the KaiBC clock was likely an adaptive strategy that ensured optimal nitrogen fixation as microbes evolved from an anaerobic to an aerobic atmosphere under nitrogen constraints.

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High‐frequency sampling captures variability in phytoplankton population‐specific periodicity, growth, and productivity

Hynes,

Winter,

Berthiaume

et al. 2024

Limnology & Oceanography

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The Hawaii Ocean Time‐series (HOT) at Station ALOHA (22.75°N, 158°W) in the North Pacific Subtropical Gyre (NPSG) serves as a critical vantage point for observing plankton biomass production and its ecological implications. However, the HOT program's near‐monthly sampling frequency does not capture shorter time scale variability in phytoplankton populations. To address this gap, we deployed the SeaFlow flow cytometer for continuous monitoring during HOT cruises from 2014 to 2021. This approach allowed us to examine variations in the surface abundance and cell carbon content of specific phytoplankton groups: the cyanobacteria Prochlorococcus, Synechococcus, and Crocosphaera as well as a range of small eukaryotic phytoplankton ( 5 μm). Our data showed that daily to monthly variability in Prochlorococcus and Synechococcus abundance matches seasonal and interannual variability, while small eukaryotic phytoplankton and Crocosphaera showed the highest seasonal and interannual fluctuations. The study also found that eukaryotic phytoplankton and Crocosphaera had higher median cellular growth rates (0.076 and , respectively) compared to Prochlorococcus and Synechococcus (0.037 and , respectively). These variances in abundance and growth rates indicate that shifts in the community structure significantly impact primary productivity in the NPSG. Our results underscore the importance of daily to monthly phytoplankton dynamics in ecosystem function and carbon cycling.

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The balance between photosynthesis and respiration explains the niche differentiation between Crocosphaera and Cyanothece

Cited by 7 publications

References 46 publications

Winter Convective Mixing Mediating Coupling of N‐Gain and ‐Loss in the Arabian Sea

Winter Convective Mixing Mediating Coupling of N‐Gain and ‐Loss in the Arabian Sea

KaiA regulates intracellular oxygen dynamics in unicellular diazotrophic cyanobacteria

High‐frequency sampling captures variability in phytoplankton population‐specific periodicity, growth, and productivity

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