Growth, iron requirements, and siderophore production in iron‐limited Synechococcus PCC 72

Wilhelm, Steven W.; Maxwell, Denis P.; Trick, Charles G.

doi:10.4319/lo.1996.41.1.0089

Cited by 94 publications

(83 citation statements)

References 25 publications

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“…It is realised that these extremely low values are biased by taking in account only dissolved Fe concentrations, ignoring kinetics of Fe. In the case of Synechococcus, cellular iron values were reported to vary over 4 orders of magnitude with changing ambient iron concentration (Wilhelm et al, 1996). A dtrueT estimate of the iron content of Synechococcus was achieved using continuous cultures resulting in an iron quotum of 0.42 Â 10 À18 M cell À1 (Wilhelm and Trick, 1995), about 100 times higher than the value reported for Synechococcus in this study.…”

Section: Fe Limitation Experimentsmentioning

confidence: 44%

“…Measurements of Fe iron quota in pico-phytoplankton are scarce and hindered by technical complications, as for example Fe adsorbed externally (Wilhelm et al, 1996), and/or the inability to measure the concentration and kinetics of the bioavailable iron pool. Minimum Fe quota (only for cultures grown at Fe replete conditions) in the three species that we tested during our study were extremely low, in the zepto-mol (10 À21 mol) cell À1 range (Table 3).…”

Section: Fe Limitation Experimentsmentioning

confidence: 99%

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Physiological responses of three species of marine pico-phytoplankton to ammonium, phosphate, iron and light limitation

Timmermans

Wagt

Veldhuis

et al. 2005

Journal of Sea Research

106

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Physiological responses of three species of marine pico-phytoplankton to ammonium, phosphate, iron and light limitation Timmermans, K.R.; Wagt, B. van der; Veldhuis, M.J.W.; Maatman, A.; de Baar, Henricus Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. AbstractExperiments were conducted with three species of marine pico-phytoplankton: Synechococcus sp. (CCMP 839), Pelagomonas calceolata (CCMP 1756) and Prasinomonas capsulatus (CCMP 1617) in order to collect physiological parameters for pico-phytoplankton to be utilised in Ocean Biogeochemical Climate Models. The main parameters to follow the effects of ammonium, phosphate, iron and light limitation were cell growth rates (A), half saturation constants for growth (K m ), N, P and Fe quota (per cell or per mol C), and photochemical quantum efficiency (F v /F m ).The nitrate and phosphate limitation experiments demonstrated that the small phytoplankton species could grow at low N and P concentrations. K m values were in the micro-molar (NH 4 + ) and sub-micro-molar (PO 4 3À ) range. N and P quota were in the femto-molar range per cell and varied from nutrient-deplete to nutrient-replete conditions. F v /F m values were only adversely affected at the lowest N and P concentrations in these experiments. In the Fe limitation experiments, it was shown that all three species were adversely affected only at extremely low Fe concentrations. Iron chelating agents had to be added to force the species in Fe limitation till ultimately growth stopped. K m values with respect to dissolved Fe were in the femto-molar range. Fe quota were in the low zepto-molar (10 À21 M) range per cell, and varied considerably from Fe limiting to Fe replete growth conditions. F v /F m values diminished only at the lowest iron concentrations. In the light limitation experiments, growth rates and photochemical quantum efficiencies were adversely affected only at irradiance levels below 10 Amol photons m À2 s À1 . These results indicate that the pico-phytoplankton species will hardly ever be completely stopped in their growth by NH 4 + , PO 4 3À, Fe or light (separately) under natural conditions. D

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Section: Fe Limitation Experimentsmentioning

confidence: 44%

Section: Fe Limitation Experimentsmentioning

confidence: 99%

Physiological responses of three species of marine pico-phytoplankton to ammonium, phosphate, iron and light limitation

Timmermans

Wagt

Veldhuis

et al. 2005

Journal of Sea Research

106

View full text Add to dashboard Cite

show abstract

“…Utilization of a standardized Redfield ratio allows for an intercomparison of results (Table 1). These requirements can be contrasted with those determined through the utilization of a solution of titanium (111)-citrate-EDTA (Hudson & More1 1989), which rapidly reduces extracellular iron and allows for a determination of iron within the cell when cells are maintained with tracer levels of ' ' Fe or jgFe (Sunda et al 1991, Wilhelm et al 1996. In all cases, cyanobactenal Fe requirements are higher than those of eukaryotic algae (Table 1).…”

Section: Effect Of Iron Availability On Cyanobacterial Growthmentioning

confidence: 95%

“…PCC 7002 (Wilhelm & Trick 1995a). Boussiba & Richmond (1980) have suggested that the degradation of cellular phycocyanin may be only a secondary effect of iron limitation; nitrogen deficiency caused by a reduction in the level of iron-containing enzymes required for nitrogen assimilation may cause the cells to degrade phycocyanin pools and utilize them as a source of N. Decreases have also been documented for cellular levels of the accessory pigments zeaxanthin and p-carotene (Wilhelm et al 1996).…”

Section: Iron-limited Cyanobacterial Physiologymentioning

confidence: 99%

Ecology of iron-limited cyanobacteria: a review of physiological responses and implications for aquatic systems

Wilhelm¹

1995

Aquat. Microb. Ecol.

134

104

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Recent studies have demonstrated that cyanobacteria are capable of responding to low levels of iron availability through alterations in cellular iron requirements and by increasing their ability to scavenge iron from the environment through the activation of siderophore-mediated high-affinity transport systems. The significant amount of evidence In the literature on siderophore production by cyanobacteria suggests that these iron-chelating compounds may b e important in the determination of iron availability in aquatic systems. This review focuses on how cyanobacteria respond to growthlimiting levels of available iron and on how siderophores potentially alter the biological availability of iron in the system thereby allowing the cyanobacteria to e x~s t at low iron availabilities. In the light of recent findings on the amount of organically complexed iron in aquatic systems, it is concluded that the production of siderophores by aquatic organisms may specifically dictate the levels of biologically available iron in some aquatic systems.

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“…This method is relatively simple, with only one time point, but the metal uptake kinetics cannot be obtained nor can cell surface adsorption, which is completed within a few minutes (Hassler et al 2004). The cells can also excrete some metabolites during the long-term exposure period; thus, the water chemistry and metal speciation might be affected, which are critical in metal accumulation (Wilhelm et al 1996;Marañón et al 2004;Wei and Ahner 2005). In the short-term exposure experiments, cellular metal accumulation is quantified at dif-1 Corresponding author (wwang@ust.hk).…”

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confidence: 99%

Fulfilling iron requirements by a coastal diatom under different temperatures and irradiances

Miao

Wang

2006

Limnol. Oceanogr.

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The strategies used by a coastal diatom, Thalassiosira pseudonana, for potentially different iron (Fe) requirements under different temperatures and irradiances were examined on the basis of three parameters: Fe uptake rate, cellspecific growth rate, and Fe efflux rate constant. These three variables determined the cellular Fe concentration, and they were all quantified under different temperatures and irradiances during long-term (days) and short-term (hours) 59 Fe exposures. Results obtained from both exposures were consistent. Although more Fe was required under the lower irradiance, Fe uptake rate decreased 1.78ϫ and 2.20ϫ as the irradiance decreased from 340 to 40 mol photons m Ϫ2 s Ϫ1 when measured by short-and long-term exposures, respectively. Under this condition, the cellspecific growth rate decreased from 1.30-1.50 to 0.51-0.63 d Ϫ1 to keep a relatively high intracellular Fe concentration under lower irradiance. The opposite trend was observed for temperature. The higher Fe requirement at higher temperature was fulfilled mainly through an increase of Fe uptake rate with increasing temperature. For example, the Fe uptake rate increased by 1.21ϫ and 2.55ϫ as the temperature increased from 15ЊC to 24ЊC in the short-and long-term exposures, respectively. In contrast, the cell-specific growth rate was relatively constant (0.92-1.06 d Ϫ1

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Growth, iron requirements, and siderophore production in iron‐limited Synechococcus PCC 72

Cited by 94 publications

References 25 publications

Physiological responses of three species of marine pico-phytoplankton to ammonium, phosphate, iron and light limitation

Physiological responses of three species of marine pico-phytoplankton to ammonium, phosphate, iron and light limitation

Ecology of iron-limited cyanobacteria: a review of physiological responses and implications for aquatic systems

Fulfilling iron requirements by a coastal diatom under different temperatures and irradiances

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