Faster growth of the major prokaryotic versus eukaryotic CO2 fixers in the oligotrophic ocean

Zubkov, Mikhail V.

doi:10.1038/ncomms4776

Cited by 53 publications

(46 citation statements)

References 41 publications

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“…Assumptions of the model, for example maximum division rates of 2 d −1 or what defines the growth irradiance, could significantly bias model results. New methods for assessing growth rates in the field may shed light on the maximal growth rates of natural phytoplankton communities (Zubkov 2014) and would directly influence modeled NPP in ecosystems models such as the CbPM. Additional work is needed to resolve discrepancies between modeled and measured rates of NPP, which despite the difference in approach, show good relative agreement.…”

Section: Discussionmentioning

confidence: 99%

Photoacclimation of natural phytoplankton communities

Graff

Westberry²,

Milligan³

et al. 2016

Mar. Ecol. Prog. Ser.

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Phytoplankton regulate internal pigment concentrations in response to light and nutrient availability. Chlorophyll a to phytoplankton carbon ratios (chl:C phyto ) are commonly reported as a function of growth irradiance (E g ) for evaluating the photoacclimation response of phytoplankton. In contrast to most culture experiments, natural phytoplankton communities experience fluctuating environmental conditions, making it difficult to compare field and lab observations. Observing and understanding photoacclimation in nature is important for deciphering changes in chl:C phyto resulting from environmental forcings and for accurately estimating net primary production (NPP) in models which rely on a parameterized description of photoacclimation. Here we employ direct analytical measurements of C phyto and parallel high-resolution biomass estimates from particulate backscattering (b bp ) and flow cytometry to investigate chl:C phyto in natural phytoplankton communities. Chl:C phyto observed over a wide range of E g in the field was consistent with photoacclimation responses inferred from satellite observations. Field-based photoacclimation observations for a mixed natural community contrast with laboratory results for single species grown in continuous light and nutrient-replete conditions. Applying a carbon-based NPP model to our field data for a north−south transect in the Atlantic Ocean results in estimates that closely match 14 C depth-integrated NPP for the same cruise and with historical records for the distinct biogeographic regions of the Atlantic Ocean. Our results are consistent with previous satellite and model observations of cells growing in natural or fluctuating light and showcase how direct measurements of C phyto can be applied to explore phytoplankton photophysiology, growth rates, and production at high spatial resolution in situ.

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Section: Discussionmentioning

confidence: 99%

Photoacclimation of natural phytoplankton communities

Graff

Westberry²,

Milligan³

et al. 2016

Mar. Ecol. Prog. Ser.

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“…Synechococcus maximum growth rates are comparable to or slighter faster than those of Prochlorococcus (25,26), with similar mechanisms of mortality (27,28). However, estimates of in situ specific growth rates are broader, between 1-6 d (29, 30), due to the varying environments Synechococcus occupies.…”

Section: Significant Potential For Hydrocarbon Production By Prochlormentioning

confidence: 97%

“…Although total population sizes of Prochlorococcus and Synechococcus remain largely stable on an annual timescale, their turnover rates are high. Prochlorococcus divide once every 1-2 d (23)(24)(25), with cellular losses balancing division in a quasi-steady-state manner. Cyanobacterial mortality can be mediated by a variety of factors, including predation by grazers or viruses, UV-induced lysis, or spontaneous cell death (18), resulting in release of organic carbon compounds, including alkanes, into the environment.…”

Section: Significant Potential For Hydrocarbon Production By Prochlormentioning

confidence: 99%

Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle

Lea‐Smith

Biller

Davey

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

174

122

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Hydrocarbons are ubiquitous in the ocean, where alkanes such as pentadecane and heptadecane can be found even in waters minimally polluted with crude oil. Populations of hydrocarbon-degrading bacteria, which are responsible for the turnover of these compounds, are also found throughout marine systems, including in unpolluted waters. These observations suggest the existence of an unknown and widespread source of hydrocarbons in the oceans. Here, we report that strains of the two most abundant marine cyanobacteria, Prochlorococcus and Synechococcus, produce and accumulate hydrocarbons, predominantly C15 and C17 alkanes, between 0.022 and 0.368% of dry cell weight. Based on global population sizes and turnover rates, we estimate that these species have the capacity to produce 2-540 pg alkanes per mL per day, which translates into a global ocean yield of ∼308-771 million tons of hydrocarbons annually. We also demonstrate that both obligate and facultative marine hydrocarbon-degrading bacteria can consume cyanobacterial alkanes, which likely prevents these hydrocarbons from accumulating in the environment. Our findings implicate cyanobacteria and hydrocarbon degraders as key players in a notable internal hydrocarbon cycle within the upper ocean, where alkanes are continually produced and subsequently consumed within days. Furthermore we show that cyanobacterial alkane production is likely sufficient to sustain populations of hydrocarbon-degrading bacteria, whose abundances can rapidly expand upon localized release of crude oil from natural seepage and human activities.cyanobacteria | hydrocarbons | hydrocarbon cycle | hydrocarbon-degrading bacteria | oil remediation

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“…Endosymbiosis of proto-chloroplasts altered their photosynthetic scaling from apparently superlinearity in cyanobacteria [22] to sublinearity in chloroplasts. These shifts are consistent with arguments proposing the observed superlinearity results from increased genome and metabolic network size associated with increasing cell size [19].…”

Section: Discussionmentioning

confidence: 99%

“…In bacteria, growing evidence suggests that rates of respiration and photosynthesis largely exhibit superlinear scaling (a . 1), with photosynthesis apparently scaling less steeply than respiration [19,21,22]-should mitochondria and chloroplasts, which evolved from bacteria, also exhibit superlinear scaling or has endosymbiotic evolution and multicellularity fundamentally altered their scaling? In unicellular eukaryotes, respiration rate exhibits linear scaling for a variety of heterotrophic and phototrophic protists [17,19,23].…”

Section: Introductionmentioning

confidence: 99%

Major evolutionary transitions of life, metabolic scaling and the number and size of mitochondria and chloroplasts

2016

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We investigate the effects of trophic lifestyle and two types of major evolutionary transitions in individuality-the endosymbiotic acquisition of organelles and development of multicellularity-on organellar and cellular metabolism and allometry. We develop a quantitative framework linking the size and metabolic scaling of eukaryotic cells to the abundance, size and metabolic scaling of mitochondria and chloroplasts and analyse a newly compiled, unprecedented database representing unicellular and multicellular cells covering diverse phyla and tissues. Irrespective of cellularity, numbers and total volumes of mitochondria scale linearly with cell volume, whereas chloroplasts scale sublinearly and sizes of both organelles remain largely invariant with cell size. Our framework allows us to estimate the metabolic scaling exponents of organelles and cells. Photoautotrophic cells and organelles exhibit photosynthetic scaling exponents always less than one, whereas chemoheterotrophic cells and organelles have steeper respiratory scaling exponents close to one. Multicellularity has no discernible effect on the metabolic scaling of organelles and cells. In contrast, trophic lifestyle has a profound and uniform effect, and our results suggest that endosymbiosis fundamentally altered the metabolic scaling of free-living bacterial ancestors of mitochondria and chloroplasts, from steep ancestral scaling to a shallower scaling in their endosymbiotic descendants.

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Faster growth of the major prokaryotic versus eukaryotic CO2 fixers in the oligotrophic ocean

Cited by 53 publications

References 41 publications

Photoacclimation of natural phytoplankton communities

Photoacclimation of natural phytoplankton communities

Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle

Major evolutionary transitions of life, metabolic scaling and the number and size of mitochondria and chloroplasts

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