Trends and Perspectives in Nitrogen Fixation Research

Postgate, J. R.

doi:10.1016/s0065-2911(08)60108-3

Cited by 12 publications

(10 citation statements)

References 43 publications

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“…It has been suggested that the production of EPS in N-limiting conditions may be a survival mechanism favouring the exclusion of oxygen and increasing nitrogenase activity (Postgate 1989). pneumoniue produces large amounts of EPS which could be expected to be an advantage in biofilm formation and nitrogen fixation.…”

Section: Discussionmentioning

confidence: 99%

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Biofilm formation by the Enterobacteriaceae: a comparison between Salmonella enteritidis, Escherichia coli and a nitrogen‐fixing strain of Klebsiella pneumoniae

Jones

Bradshaw

1996

Journal of Applied Bacteriology

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A simple laboratory reactor, which simulates biofilm formation in pipes, was used to compare biofilm formation by three members of the Enterobacteriaceae, namely, an environmental, nitrogen-fixing strain of Klebsiella pneumoniae, a pathogen, Salmonella enteritidis, and a faecal indicator, Escherichia coli. All three attached to CVCP pipe surfaces in the reactor and formed substantial biofilm populations of over a million bacteria cm-2 within 24 h. These populations increased by approximately 10-fold over the next 48 h. Estimates of the numbers of metabolically active cells and the ratios of viable to direct counts showed that Kl. pneumoniae formed the densest and most metabolically active biofilms, followed by Salm. enteritidis and E. coli, respectively. Nitrogen fixation and polysaccharide production (EPS) by Kl. pneumoniae occurred only in mature biofilms and were of no selective advantage in the initiation of biofilms. Despite producing more EPS the rate of attachment of Salm. enteritidis was lower than for Kl. pneumoniae.

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Section: Discussionmentioning

confidence: 99%

“…pneumoniue occurs in biofilms (Table l), it is limited to mature biofilms. This may be because nitrogen fixation is an anaerobic process (Postgate 1989) and requires the development of anaerobic or microaerobic microsites within the biofilm before it can proceed. Nitrogen fixation by heterotrophic bacteria, such as KI.…”

Section: Discussionmentioning

confidence: 99%

Biofilm formation by the Enterobacteriaceae: a comparison between Salmonella enteritidis, Escherichia coli and a nitrogen‐fixing strain of Klebsiella pneumoniae

Jones

Bradshaw

1996

Journal of Applied Bacteriology

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“…Postgate [89] stated that, to be convincing, the report of a new N2-fixing system must fulfill two elementary criteria: it must be unequivocally free of known diazotrophs and must demonstrate significant uptake of ~SN 2. This test, however, is not as sensitive as the acetylene reduction assay and requires access to either a mass spectrometer or an emission spectrometer.…”

Section: Determinative Testsmentioning

confidence: 99%

N2-fixing pseudomonads and related soil bacteria

Chan

1994

FEMS Microbiology Reviews

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Pseudomonas-like organisms form a highly heterogeneous and ubiquitous group of bacteria. Recent identification of an authentic P~eudomonas genus should help to decrease difficulties which arose from taxonomic uncertainties. Further difficulties in recognising N2-fixing Pseudomonas species lie in the confirmation of diazotrophy. Optimised conditions are often needed for the detection of nitrogenase activity since it is controlled by specific environmental factors and physiological requirements. However, genetically constructed N2-fixing strains from authentic Pseudomonas species have demonstrated that at least some members of the genus possess mechanisms to accommodate and express nil (N z fixation) genes from a well-studied diazotroph, Klebsiella pneumoniae. Renowned for their catabolic versatility, pseudomonads can use a wide range of carbon and energy substrates. Hence, potential N2-fixing pseudomonads are conceivably less limited by carbon and energy sources available in the environment compared to other N2-fixing organisms. Pseudomonas species dominate in the rhizosphere of some plants from which isolates have been shown to be diazotrophic. Several strains are also chemolithotrophs, capable of using H 2 as energy and electron source and CO2 as carbon source. Besides assays for N2-fixing activity, DNA hybridisation to the well conserved molybdo-nitrogenase structural gene probe is an indicator of diazotrophy. However, absence of hybridisation to this probe, despite N 2 fixation activity, has been reported. Although the genetics of N 2 fixation in pseudomonads have hardly been studied, some nif genes have been shown to be plasmid-borne. Pseudomonas species are also predominant soil denitrifiers, reducing nitrate and nitrite to gaseous forms of nitrogen during anaerobic respiration. Hence, they play an important role in the global biological nitrogen cycle. Several diazotrophic species including a few pseudomonads can also denitrify. The potential contribution by Ne-fixing pseudomonads to the sinks and sources of soil nitrogen is considered small in the short term but essentially remains unclear in the absence of experimental data. Reliable rapid methods for their specific enumeration are indispensable for assessing their population dynamics and ascertaining their ecological significance.

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“…thermoautotrophicus is a new diazotrophic chemolithoautotroph that feeds on CO or H2 plus CO2. Postgate (25) pointed out that a convincing report of a new N2-fixing system must fulfill two elementary criteria: the systems or cultures (i) must be unequivocally free of known diazotrophs and (ii) must demonstrate significant uptake of 15N2. Both criteria are met by S. thermoautotrophicus.…”

Section: Resultsmentioning

confidence: 99%

“…Since it is known that nif structural genes are conserved in diazotrophic bacteria (21,25,31), we were interested in determining whether nif-homologous genes were present in S. thermoautotrophicus. We probed S. thernoautotrophicus total DNA with appropriate gene probes from K. pneumoniae (see Materials and Methods).…”

Section: Resultsmentioning

confidence: 99%

Chemolithoautotrophic assimilation of dinitrogen by Streptomyces thermoautotrophicus UBT1: identification of an unusual N2-fixing system

1992

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Streptomyces thermoautotrophicus UBT1, which was isolated previously from a burning charcoal pile, was shown to utilize N2 as a sole nitrogen source when growing chemolithoautotrophicaily with CO or H2 plus CO2 under aerobic conditions at 65°C. Doubling times under diazotrophic conditions were 10 h. S. thermoautotrophicus is a new CO-or H2-oxidizing, obligately chemolithoautotrophic, thermophilic, free-living, aerobic, N2-fixing streptomycete. Its ability to fix N2 was also evident from (i) the incorporation of substantial amounts of 15N2 (about 13%) into cell material, (ii) the formation of H2 during diazotrophic growth, (iii) the repression of 15N2 assimilation and H2 formation by ammonia, and (iv) culture growth yields with N2 as a nitrogen source that were significantly higher than those without any added nitrogen compounds (ca. 2.4 versus <0.1 mg [dry weight]). The N2-fixing system of S. thermoautotrophicus exhibited several properties not apparent in the diazotrophic bacteria studied so far, since it was (i) incapable of reducing acetylene to ethylene or ethane and (ii) resistant to inhibition by acetylene or ethylene (5% [vol/vol] each), CO (40 to 70%o [vol/vol]), or H2 (40%o [vol/vol]). Under stringent conditions, n(fH and nifDK gene probes from KiebsieUla pneumoniae did not hybridize with total DNA from S. thermoautotrophicus.Many eubacteria (24) and archaebacteria (3,4,20) are capable of fixing N2 into cell material. Most diazotrophic bacteria are heterotrophs. Some strains of Xanthobacter spp. can assimilate N2 when growing chemolithoautotrophically with H2 plus CO2 (12, 16). Bacterial strain S17 was shown to grow under a gas atmosphere containing H2, 02, CO, and N2 (22,23), and the authors reported the chemolithoautotrophic utilization of H2, CO, and N2 as sources of energy, carbon, and nitrogen, respectively. They also reported on another isolate (strain A305) that could fix N2 with CO serving as the sole source of carbon and energy under aerobic, chemolithoautotrophic conditions (30).Recently, we described the isolation of the thermophilic CO-and H2-utilizing aerobe Streptomyces thernoautotrophicus UBT1 from the covering soil of a burning charcoal pile (11). S. thermoautotrophicus is a gram-positive, obligate chemolithoautotroph, growing best at 65°C. There are several indications, e.g., different electron acceptor specificities (11), N-terminal amino acid sequences, and the subunit structure of CO dehydrogenase (18), that set CO oxidation in S. thermoautotrophicus apart from this process in the "classical" carboxidotrophic bacteria.In this paper, we describe the ability of S. thermoautotrophicus to fix N2 under chemolithoautotrophic conditions with CO or H2 plus CO2 as sources of carbon and energy and some unusual properties of its N2-fixing system. chemolithoautotrophically with NH4C1 (1.5 g/liter) as the nitrogen source as described previously (11). Growth under N2-fixing conditions was accomplished in an N-free medium (NFIX): solution A consisted of MgSO4. 7H20 (0.3 g), NaCl (0.2 g), CaCl2. 2H...

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Trends and Perspectives in Nitrogen Fixation Research

Cited by 12 publications

References 43 publications

Biofilm formation by the Enterobacteriaceae: a comparison between Salmonella enteritidis, Escherichia coli and a nitrogen‐fixing strain of Klebsiella pneumoniae

Biofilm formation by the Enterobacteriaceae: a comparison between Salmonella enteritidis, Escherichia coli and a nitrogen‐fixing strain of Klebsiella pneumoniae

N2-fixing pseudomonads and related soil bacteria

Chemolithoautotrophic assimilation of dinitrogen by Streptomyces thermoautotrophicus UBT1: identification of an unusual N2-fixing system

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