Anaerobic Metabolism in Haloferax Genus

Torregrosa-Crespo, Javier; Martínez‐Espinosa, Rosa María; Esclapez, Julia; Bautista, Vanesa; Pire, Carmen; Camacho, Mónica; Richardson, David J.; Bonete, Marı́a José

doi:10.1016/bs.ampbs.2016.02.001

Cited by 38 publications

(52 citation statements)

References 137 publications

(126 reference statements)

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“…The strains used in this work have all been fully sequenced, the genes encoding the central denitrification apparatus have been identified and the biochemistry of some of the core enzymes have been explored (Bickel-Sandkötter and Ufer, 1995;Inatomi and Hochstein, 1996;Lledó et al, 2004;Torregrosa-Crespo et al, 2016). Apart from the lack of nos genes in H. volcanii, the relatively subtle differences in the respective functional genes and amino acid sequences of the main enzymes of the pathway (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Denitrifying haloarchaea within the genus Haloferax display divergent respiratory phenotypes, with implications for their release of nitrogenous gases

Torregrosa-Crespo

Pire

Martínez‐Espinosa

et al. 2018

Environmental Microbiology

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Summary Haloarchaea are extremophiles, generally thriving at high temperatures and salt concentrations, thus, with limited access to oxygen. As a strategy to maintain a respiratory metabolism, many halophilic archaea are capable of denitrification. Among them are members of the genus Haloferax, which are abundant in saline/hypersaline environments. Three reported haloarchaeal denitrifiers, Haloferax mediterranei, Haloferax denitrificans and Haloferax volcanii, were characterized with respect to their denitrification phenotype. A semi‐automatic incubation system was used to monitor the depletion of electron acceptors and accumulation of gaseous intermediates in batch cultures under a range of conditions. Out of the species tested, only H. mediterranei was able to consistently reduce all available N‐oxyanions to N2, while the other two released significant amounts of NO and N2O, which affect tropospheric and stratospheric chemistries respectively. The prevalence and magnitude of hypersaline ecosystems are on the rise due to climate change and anthropogenic activity. Thus, the biology of halophilic denitrifiers is inherently interesting, due to their contribution to the global nitrogen cycle, and potential application in bioremediation. This work is the first detailed physiological study of denitrification in haloarchaea, and as such a seed for our understanding of the drivers of nitrogen turnover in hypersaline systems.

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Section: Discussionmentioning

confidence: 99%

“…The biodiversity under hypersalinity is lower than in other, less extreme environments (Oren, 2002), but higher than one might expect. All three domains of Life are represented, but Haloarchaea have been found to dominate when the salt concentration exceeds 16% (Andrei et al, 2012;Edbeib et al, 2016;Torregrosa-Crespo et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Denitrifying haloarchaea within the genus Haloferax display divergent respiratory phenotypes, with implications for their release of nitrogenous gases

Torregrosa-Crespo

Pire

Martínez‐Espinosa

et al. 2018

Environmental Microbiology

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“…Potential uses of these specific antibiotics in biotechnology, pharmacy, and biomedicine produced by haloarchaea remain unexplored. The cells themselves are also promising systems to explore other uses such as biosensors or soil/water bioremediation strategies [8,103]. Nevertheless, great effort must be made in the near future to scale-up the engineering tools required to produce biocompounds from haloarchaea at high concentrations or to use haloarchaeal whole cells for biotechnological purposes at large scale.…”

Section: Discussionmentioning

confidence: 99%

Biocompounds from Haloarchaea and Their Uses in Biotechnology

Torregrosa-Crespo¹,

Galiana²,

MaríaMartínez-Espinosa³

2017

Archaea - New Biocatalysts, Novel Pharmaceuticals and Various Biotechnological Applications

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New advances in the understanding of haloarchaea physiology, metabolism, biochemistry, and molecular biology show that these kinds of microorganisms produce several compounds in response to the extreme conditions of their ecosystems. Thus, the complete metabolic and genetic machineries are fully adapted to nutrient starvation, high sun radiation, and high ionic strength. Due to these adaptations, some of the primary and secondary metabolites produced by haloarchaea are of high interest in terms of potential biotechnological uses. The principal goal of the chapter is to present a review about the main characteristics of these biocompounds and their potential uses in biomedicine, pharmacy, and industry.

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“…volcanii, and Hfx. denitrificans) [72] (Figure 4). In this pathway, nitrate (NO 3 − ) is used by the cells as the final electron acceptor under anoxia.…”

Section: Expression Of Metalloenzymes From Haloarchaea: Denitrificatimentioning

confidence: 99%

“…Some denitrifiers are complete, i.e., nitrate is fully reduced to dinitrogen thanks to four key enzymes: respiratory nitrate reductase (Nar), respiratory nitrite reductase (Nir), nitric oxide reductase (Nor), and nitrous oxide reductase (Nos). However, the process is often incomplete (partial denitrification), leading to the release of the gaseous intermediates NO and N 2 O, which affect the environment [72][73][74].…”

Section: Expression Of Metalloenzymes From Haloarchaea: Denitrificatimentioning

confidence: 99%

Heterologous and Homologous Expression of Proteins from Haloarchaea: Denitrification as Case of Study

Martínez‐Espinosa

2019

IJMS

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Haloarchaea (halophilic microbes belonging to the Archaea domain) are microorganisms requiring mid or even high salt concentrations to be alive. The molecular machinery of these organisms is adapted to such conditions, which are stressful for most life forms. Among their molecular adaptations, halophilic proteins are characterized by their high content of acidic amino acids (Aspartate (Asp) and glumate (Glu)), being only stable in solutions containing high salt concentration (between 1 and 4 M total salt concentration). Recent knowledge about haloarchaeal peptides, proteins, and enzymes have revealed that many haloarchaeal species produce proteins of interest due to their potential applications in biotechnology-based industries. Although proteins of interest are usually overproduced in recombinant prokaryotic or eukaryotic expression systems, these procedures do not accurately work for halophilic proteins, mainly if such proteins contain metallocofactors in their structures. This work summarizes the main challenges of heterologous and homologous expression of enzymes from haloarchaea, paying special attention to the metalloenzymes involved in the pathway of denitrification (anaerobic reduction of nitrate to dinitrogen), a pathway with significant implications in wastewater treatment, climate change, and biosensor design.

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Anaerobic Metabolism in Haloferax Genus

Cited by 38 publications

References 137 publications

Denitrifying haloarchaea within the genus Haloferax display divergent respiratory phenotypes, with implications for their release of nitrogenous gases

Denitrifying haloarchaea within the genus Haloferax display divergent respiratory phenotypes, with implications for their release of nitrogenous gases

Biocompounds from Haloarchaea and Their Uses in Biotechnology

Heterologous and Homologous Expression of Proteins from Haloarchaea: Denitrification as Case of Study

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