Iron acquisition by cyanobacteria: siderophore production and iron transport by Anabaena

Lammers, Peter J.

doi:10.15760/etd.407

Cited by 3 publications

(5 citation statements)

References 70 publications

(43 reference statements)

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“…Kinetics of siderophore-mediated iron uptake in Anabaena have been investigated by Lammers (1982), who found the apparent KM for schizokinen uptake to be very low, about 36 nM. This, coupled with the fact that the formation constant of the ferric schizokinen complex is very high (Kf=10 23 ), means that uptake is probably not the rate-limiting step for iron acquisition by siderophores.…”

Section: Q)mentioning

confidence: 99%

“…With a substrate turnover rate of only 1.25 N 2 ·sec-1 (Postgate 1987), large amounts of the enzyme must be available to support rapid growth rates on gaseous nitrogen. The net effect of these two interacting factors is that nitrogen fixing laboratory cultures of cyanobacteria may require iron at levels of up to an order of magnitude higher than the same species grown on fixed nitrogen sources (Lammers 1982).…”

Section: Introductionmentioning

confidence: 99%

“…Under nitrogen-fixing conditions, iron is required at levels far exceeding those needed for growth on fixed nitrogen sources (Lammers 1982, Raven 1988). Large amounts of iron are required both for synthesis of the nitrogenase enzyme (Averill and Orme-Johnson 1978) and to support the increased levels of photosynthetic electron transport necessary to provide reductant and ATP during diazotrophic growth (Raven 1988).…”

mentioning

confidence: 99%

“…Another alternative assay system is a bioassay using a mutant of the bacterium Arthrobacter flavescens (strain JG-9) which is a siderophore auxotroph. Since this organism is unable to take up iron without an exogenous source of chelator, siderophore production by algal cultures can be verified simply by adding culture filtrate to bacterial plate cultures and observing whether or not growth occurs (Lankford 1973, Lammers 1982. This procedure, however, has no advantages over the CAS/HDTMA assay since it also does not identify the type of siderophore produced and requires lengthy bacterial culture incubations and sterile techniques.…”

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confidence: 99%

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Nitrogen and iron interactions in filamentous cyanobacteria

Hutchins¹

2000

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Also investigated was the relationship between siderophore-mediated iron uptake and diazotrophy in Anabaena. It was found that the strain of Anabaena used in these experiments (PCC strain 7120) is unable to make siderophores and fix nitrogen simultaneously, suggesting that previous work linking these two capabilites to competitive dominance may be in error or misinterpreted.The final aspect of this problem which was examined was the possibilty 2 of gratuitous repression of Anabaena siderophore production by manganese in the manner previously described by other investigators in E. coli. No evidence for this type of molecular regulation was found, although maganese did appear to bind to siderophore in the water.

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Section: Q)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Nitrogen and iron interactions in filamentous cyanobacteria

Hutchins¹

2000

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“…For example, NtcA regulates the concentration dependent iron uptake by controlling the expression of the furA gene in Anabaena 7120 [28]. Despite dozens of papers being published on this topic [29–32], the pathway and mechanism of utilizing different forms of iron complexes by cyanobacteria and the ultimate fate of iron in water have not been well understood. Therefore, this work is devoted to investigating the effects of iron form and concentration on absorption by A. flos-aquae .…”

Section: Introductionmentioning

confidence: 99%

Effect of four kinds of complexing iron on the process of iron uptake by Anabaena flos-aquae

Qiu

Wang²,

Huang

et al. 2020

Microbiology

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Iron (Fe), which is a necessary micronutrient for algal growth, plays an important role in the physiological metabolism and enzymatic reactions of algae. This study aimed to investigate the absorption process of four kinds of complexing iron absorbed by Anabaena flos-aquae. Results showed that the absorptive capacity of A. flos-aquae to complex iron was inversely proportional to the stability of the complex bond of complex iron. Complex iron with weak binding ability can be quickly adsorbed by A. flos-aquae. The absorptive rate was as follows: ferric humate, ferric oxalate >ammonium ferric citrate >EDTA Fe. For EDTA-Fe with a strong binding ability, a moderate iron concentration (e.g. 0.6 mg l−1) is favourable for iron uptake by A. flos-aquae. Our experiments also revealed that the process of separating iron from complex iron before entering algal cells was probably as follows: iron complexed with organic ligands were firstly adsorbed on the surface of algae cells; afterwards, iron ions were captured by organic matter on the surface of algae cells, accompanied by the rupture of the bond between Fe3+ and ligand; finally, the Fe3+ entered into the cell of algae while the organic ligands returned to the medium.

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Responses of lake phytoplankton to micronutrient enrichment: a study in two New Zealand lakes and an analysis of published data

2008

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Natural and anthropogenic changes in nutrient concentrations can affect phytoplankton in marine and freshwater environments. However, potential micronutrient limitation of phytoplankton productivity in fresh waters is often overlooked. To investigate the responses of lake phytoplankton to micronutrient enrichment, we conducted a study in two contrasting New Zealand lakes, and analysed data from the published international literature. We undertook nutrient enrichment bioassays of phytoplankton communities sampled from a mesotrophic reservoir and an eutrophic coastal lake to determine the relative occurrence of micronutrient (iron, boron, cobalt, copper, molybdenum) and macronutrient (nitrogen, phosphorus) limitation. In the mesotrophic reservoir, phytoplankton productivity was phosphorus limited. No evidence of micronutrient limitation was found in six bioassays in summer. In the eutrophic lake, tenfold enrichment of ambient micronutrient concentrations increased the primary productivity in four of 11 bioassays. During a cyanobacterial bloom in the eutrophic lake, experimental enrichment with boron, cobalt, copper or molybdenum increased primary productivity by 40 %. These four micronutrients are commonly applied as agricultural fertiliser in the lakes catchment. Nitrogen or phosphorus enrichment had no effect on phytoplankton productivity at this time. Micronutrient limitation has been reported in more than 40 lakes internationally, and our analysis of published data suggests that the prevalence of micronutrient limitation is unrelated to lake size or trophic state. As micronutrient enrichment can significantly increase phytoplankton productivity in a range of lakes types, the potential contribution of micronutrient enrichment to eutrophication should not be overlooked.

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Iron acquisition by cyanobacteria: siderophore production and iron transport by Anabaena

Cited by 3 publications

References 70 publications

Nitrogen and iron interactions in filamentous cyanobacteria

Nitrogen and iron interactions in filamentous cyanobacteria

Effect of four kinds of complexing iron on the process of iron uptake by Anabaena flos-aquae

Responses of lake phytoplankton to micronutrient enrichment: a study in two New Zealand lakes and an analysis of published data

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