Nutrition of the Halophilic Archaebacterium, Haloferax volcanii

Kauri, Tiiu; Wallace, Rebecca; Kushner, D. J.

doi:10.1016/s0723-2020(11)80174-8

Cited by 51 publications

(36 citation statements)

References 4 publications

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“…CDM was a modification of that described by Kauri et al (9) in which glycerol and succinate were replaced with 30 mM trisodium citrate. Rich medium was as described in reference 6.…”

Section: Methodsmentioning

confidence: 99%

Transcriptionally active regions in the genome of the archaebacterium Haloferax volcanii

Trieselmann

Charlebois

1992

J Bacteriol

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TranscriptionaUly active regions of the Haloferax vokcanii genome were mapped by hybridization of radiolabeled cDNA to Southern blots of our minimal set of overlapping cosmid clones covering 96% of the 4.1-Mbp genome. Transcription during exponential growth occurred in nearly every region of the 2,920-kbp chromosome. Large parts of the 690-and the 86-kbp plasmids were transcribed, but the 440-kbp plasmid showed little expression. Transcription after a 40-min heat shock at 65°C was generally reduced, apart from a smal set of strongly expressed loci all situated on the chromosome.A high-resolution physical map of the 4.1-Mbp genome of the archaebacterium Haloferax volcanii DS2 has been recently completed (3). The genome is partitioned into five circular replicons: a chromosome of 2,920 kbp and four plasmids of 690, 440, 86, and 6.4 kbp. The detailed study of halobacterial genome structure is useful in that it provides an archaebacterial data base for comparative genome analysis, and it addresses the issue of the dynamics and evolution of a genome rich in insertion elements (4,8,15,16) and plasmids.We and our collaborators are interested in mapping genes to the physical framework of overlapping cosmid clones which currently cover 96% of the H. volcanii genome. The following three approaches have been used: (i) hybridization of Southern blots of digested cosmid clones by using bulk probes (tRNA or insertion elements) has allowed the mapping of families of genes (4), (ii) individual cloned halobacterial genes have been mapped by homologous or heterologous hybridization (3), and (iii) complementation of auxotrophic mutants with cosmid clone DNA has mapped 140 mutations to 35 loci (4,5,10).With the goal of further understanding the genome of H. volcanii, we designed an experiment to find those loci most transcriptionally active under different physiological conditions by synthesizing radiolabeled cDNA and hybridizing it to Southern blots of digests of our minimal set of overlapping cosmid clones. This report describes the transcriptional organization of the genome of a culture in exponential growth (in chemically defined medium [CDM] and in complex medium) and compares it with that of a culture experiencing heat shock. MATERIALS AND METHODSGrowth media and conditions. CDM was a modification of that described by Kauri et al. (9) in which glycerol and succinate were replaced with 30 mM trisodium citrate. Rich medium was as described in reference 6. Cultures (50 ml) were grown at 45°C with shaking in 250-ml Erlenmeyer flasks. Cells were harvested during exponential growth (A540, 1.6) in rich medium, during exponential growth (A540, * Corresponding author.1.0) in CDM, or after exponential growth (A540, 1.0) in CDM followed by a 40-min heat shock at 65°C with occasional agitation.RNA extraction. Cells were quick-chilled to -15°C by immersing and swirling the flask for 2 min in a salted ice-water bath before the culture was centrifuged at -10 to -15°C for 10 min at 6,000 x g. The cell pellet was suspended in 0.25 ml of col...

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“…CDM was a modification of that described by Kauri et al (9) in which glycerol and succinate were replaced with 30 mM trisodium citrate. Rich medium was as described in reference 6.…”

Section: Methodsmentioning

confidence: 99%

Transcriptionally active regions in the genome of the archaebacterium Haloferax volcanii

Trieselmann

Charlebois

1992

J Bacteriol

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“…H. hispanica strain ATCC 33960 was grown under aerobic conditions at 37°C in a 10-l flask using an air pump or in shaken 1-l flasks on a chemically defined medium (Kauri et al, 1990) with acetate (0.2%, w/v), pyruvate (0.2%) or acetate (0.2%) plus pyruvate (0.2%) as carbon sources. For the cultivation of the uracil auxotrophic (pyrF-deleted) strain DF60 (Liu et al, 2011a) and its derivatives, uracil (stock solution 50 mg ml − 1 , dissolved in DMSO) was added at a concentration of 50 mg l − 1 .…”

Section: Microbial Strains and Culture Conditionsmentioning

confidence: 99%

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

et al. 2015

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Haloarchaea (class Halobacteria) live in extremely halophilic conditions and evolved many unique metabolic features, which help them to adapt to their environment. The methylaspartate cycle, an anaplerotic acetate assimilation pathway recently proposed for Haloarcula marismortui, is one of these special adaptations. In this cycle, acetyl-CoA is oxidized to glyoxylate via methylaspartate as a characteristic intermediate. The following glyoxylate condensation with another molecule of acetylCoA yields malate, a starting substrate for anabolism. The proposal of the functioning of the cycle was based mainly on in vitro data, leaving several open questions concerning the enzymology involved and the occurrence of the cycle in halophilic archaea. Using gene deletion mutants of H. hispanica, enzyme assays and metabolite analysis, we now close these gaps by unambiguous identification of the genes encoding all characteristic enzymes of the cycle. Based on these results, we were able to perform a solid study of the distribution of the methylaspartate cycle and the alternative acetate assimilation strategy, the glyoxylate cycle, among haloarchaea. We found that both of these cycles are evenly distributed in haloarchaea. Interestingly, 83% of the species using the methylaspartate cycle possess also the genes for polyhydroxyalkanoate biosynthesis, whereas only 34% of the species with the glyoxylate cycle are capable to synthesize this storage compound. This finding suggests that the methylaspartate cycle is shaped for polyhydroxyalkanoate utilization during carbon starvation, whereas the glyoxylate cycle is probably adapted for growth on substrates metabolized via acetyl-CoA.

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“…The final growth yields obtained were somewhat variable (compare Figs 1 and 2). To examine what factors might limit anaerobic growth of Haloferax volcanii when excess fumarate (40 mM) was added, the effect of different potential electron donors for respiration -acetate, glycerol, and L-glutamate -was examined (Kauri et al, 1990). No increase in growth yield was observed, and when the stationary growth phase was reached, between 11 and 23 mwfumarate remained in the culture supernatant.…”

Section: Resultsmentioning

confidence: 99%

“…This discrepancy may be accounted for by the assimilatory use of succinate or fumarate by the cells. Halojerax volcanii, as well as a variety of other halophilic archaeobacteria, grows well using succinate as the sole or supplementary carbon source (Grant & Larsen, 1989;Kauri et al, 1990), and membrane transport systems for both succinate and fumarate have been detected in Halobacterium, Haloarcula and Halococcus strains Zvyagintseva et al, 1984).…”

Section: Resultsmentioning

confidence: 99%

Anaerobic growth of halophilic archaeobacteria by reduction of fumarate

Oren

1991

Journal of General Microbiology

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A number of strains of halophilic archaeobacteria of the genera Halobacterium and Haloferax were able to grow anaerobically using fumarate as electron acceptor. The species showing the best anaerobic growth with fumarate were Haloferax volcanii and Haloferax denitrijicans. The two Haloarcula species tested did not show anaerobic growth enhancement with fumarate. During anaerobic growth of Haloferax trolcanii in the presence of fumarate, succinate accumulated in the medium with a stoichiometry of only 0-16-0-23 mmol succinate per mmol fumarate consumed; this can be explained by the use of succinate for assimilatory purposes. The ability to reduce fumarate to succinate did not correlate with the ability to grow anaerobically using nitrate, dimethylsulphoxide or trimethylamine N-oxide as terminal electron acceptors. Anaerobic respiration with fumarate as electron acceptor supplies the halophilic archaeobacteria with an additional mode of energy generation in the absence of molecular oxygen.

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Nutrition of the Halophilic Archaebacterium, Haloferax volcanii

Cited by 51 publications

References 4 publications

Transcriptionally active regions in the genome of the archaebacterium Haloferax volcanii

Transcriptionally active regions in the genome of the archaebacterium Haloferax volcanii

The methylaspartate cycle in haloarchaea and its possible role in carbon metabolism

Anaerobic growth of halophilic archaeobacteria by reduction of fumarate

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