N2 Fixation by non-heterocystous cyanobacteria1

Bergman, Birgitta; Gallon, John; Rai, Amar; Stal, Lucas J.

doi:10.1111/j.1574-6976.1997.tb00296.x

Cited by 165 publications

(74 citation statements)

References 216 publications

(424 reference statements)

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“…In some filamentous cyanobacteria, nitrogen fixation is restricted to specialized cells (called heterocysts), which differentiate as consequence of nitrogen starvation. In cyanobacteria, up to three enzymes can be directly involved in hydrogen metabolism: nitrogenase(s) which produces H 2 concomitantly with nitrogen fixation, a membrane-bound uptake hydrogenase which re-oxidizes the H 2 evolved by nitrogenase, and the of molecular hydrogen and reduction of protons (for reviews, see Houchins 1984;Schulz 1996;Bergman et al 1997;Appel and Schulz 1998;Hansel and Lindblad 1998;Tamagnini et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Cyanobacterial H2 production ? a comparative analysis

Schütz

Happe

Troshina

et al. 2004

Planta

178

108

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Several unicellular and filamentous, nitrogen-fixing and non-nitrogen-fixing cyanobacterial strains have been investigated on the molecular and the physiological level in order to find the most efficient organisms for photobiological hydrogen production. These strains were screened for the presence or absence of hup and hox genes, and it was shown that they have different sets of genes involved in H(2) evolution. The uptake hydrogenase was identified in all N(2)-fixing cyanobacteria, and some of these strains also contained the bidirectional hydrogenase, whereas the non-nitrogen fixing strains only possessed the bidirectional enzyme. In N(2)-fixing strains, hydrogen was mainly produced by the nitrogenase as a by-product during the reduction of atmospheric nitrogen to ammonia. Therefore, hydrogen production was investigated both under non-nitrogen-fixing conditions and under nitrogen limitation. It was shown that the hydrogen uptake activity is linked to the nitrogenase activity, whereas the hydrogen evolution activity of the bidirectional hydrogenase is not dependent or even related to diazotrophic growth conditions. With regard to large-scale hydrogen evolution by N(2)-fixing cyanobacteria, hydrogen uptake-deficient mutants have to be used because of their inability to re-oxidize the hydrogen produced by the nitrogenase. On the other hand, fermentative H(2) production by the bidirectional hydrogenase should also be taken into account in further investigations of biological hydrogen production.

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Section: Introductionmentioning

confidence: 99%

Cyanobacterial H2 production ? a comparative analysis

Schütz

Happe

Troshina

et al. 2004

Planta

178

108

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“…These organisms are related to members of the orders Nostocales and Oscillatoriales, known N-fixers (Bergman et al, 1997). The emergence of cyanobacteria coincides with an increase in N fixation activity: from ~0.5 ng N fixed/cm 2 /h in the most recently exposed soils, to ~5.3 ng N fixed/cm 2 /h at 8 yr (Fig.…”

mentioning

confidence: 97%

Functional shifts in unvegetated, perhumid, recently-deglaciated soils do not correlate with shifts in soil bacterial community composition

et al. 2009

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Past work in recently deglaciated soils demonstrates that microbial communities undergo shifts prior to plant colonization. To date, most studies have focused on relatively 'long' chronosequences with the ability to sample plant-free sites over at least 50 years of development. However, some recently deglaciated soils feature rapid plant colonization and questions remain about the relative rate of change in the microbial community in the unvegetated soils of these chronosequences. Thus, we investigated the forelands of the Mendenhall Glacier near Juneau, AK, USA, where plants rapidly establish. We collected unvegetated samples representing soils that had been ice-free for 0, 1, 4, and 8 years. Total nitrogen (N) ranged from 0.00 approximately 0.14 mg/g soil, soil organic carbon pools ranged from 0.6 approximately 2.3 mg/g soil, and both decreased in concentration between the 0 and 4 yr soils. Biologically available phosphorus (P) and pH underwent similar dynamics. However, both pH and available P increased in the 8 yr soils. Nitrogen fixation was nearly undetectable in the most recently exposed soils, and increased in the 8 yr soils to approximately 5 ng N fixed/cm(2)/h, a trend that was matched by the activity of the soil N-cycling enzymes urease and beta-l,4-N-acetyl-glucosa-minidase. 16S rRNA gene clone libraries revealed no significant differences between the 0 and 8 yr soils; however, 8 yr soils featured the presence of cyanobacteria, a division wholly absent from the 0 yr soils. Taken together, our results suggest that microbes are consuming allochtonous organic matter sources in the most recently exposed soils. Once this carbon source is depleted, a competitive advantage may be ceded to microbes not reliant on in situ nutrient sources.

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“…It is difficult to explain how cyanobacterial species without heterocysts can fix nitrogen in an oxic environment, as the nitrogenase enzyme should be inactivated by oxygen, but behavioural and metabolic strategies as well as structural barriers may facilitate oxic nitrogen fixation (Bergman et al 1997). Some cyanobacteria even seem to most active during illumination (Church et al 2005), when oxygen is produced within the cells.…”

Section: Nitrogen Fixationmentioning

confidence: 99%

Nitrogen transformations in stratified aquatic microbial ecosystems

Revsbech

Risgaard-Petersen²,

Schramm

et al. 2006

Antonie van Leeuwenhoek

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New analytical methods such as advanced molecular techniques and microsensors have resulted in new insights about how nitrogen transformations in stratified microbial systems such as sediments and biofilms are regulated at a microm-mm scale. A large and ever-expanding knowledge base about nitrogen fixation, nitrification, denitrification, and dissimilatory reduction of nitrate to ammonium, and about the microorganisms performing the processes, has been produced by use of these techniques. During the last decade the discovery of anammmox bacteria and migrating, nitrate accumulating bacteria performing dissimilatory reduction of nitrate to ammonium have given new dimensions to the understanding of nitrogen cycling in nature, and the occurrence of these organisms and processes in stratified microbial communities will be described in detail.

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N2 Fixation by non-heterocystous cyanobacteria1

Cited by 165 publications

References 216 publications

Cyanobacterial H2 production ? a comparative analysis

Cyanobacterial H2 production ? a comparative analysis

Functional shifts in unvegetated, perhumid, recently-deglaciated soils do not correlate with shifts in soil bacterial community composition

Nitrogen transformations in stratified aquatic microbial ecosystems

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