Aerotolerance of strictly anaerobic microorganisms and factors of defense against oxidative stress: A review

Methanosarcina barkeri is a strictly anaerobic methanogenic archaeon, which can survive oxidative stress. The oxidative stress agent paraquat (PQ) suppressed growth of M. barkeri at concentrations of 50–200 μM. Hydrogen peroxide (H2O2) inhibited growth at concentrations of 0.4–1.6 mM. Catalase activity in cell-free extracts of M. barkeri increased about threefold during H2O2 stress (1.3 mM H2O2, 2–4 h exposure) and nearly twofold during superoxide stress (160 μM PQ, 2 h exposure). PQ (160 μM, 2–4 h exposure) and H2O2 (1.3 mM, 2 h exposure) also influenced superoxide dismutase activity in cell-free extracts of M. barkeri. Dot-blot analysis was performed on total RNA isolated from H2O2- and PQ-exposed cultures, using labelled internal DNA fragments of the sod and kat genes. It was shown that H2O2 but not PQ strongly induced up-regulation of the kat gene. PQ and to a lesser degree H2O2 induced the expression of superoxide dismutase. The results indicate the regulation of the adaptive response of M. barkeri to different oxidative stresses.

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Cytochrome bd Oxidase, Oxidative Stress, and Dioxygen Tolerance of the Strictly Anaerobic Bacterium Moorella thermoacetica

Journal of Bacteriology ◽

10.1128/jb.187.6.2020-2029.2005 ◽

2005 ◽

Vol 187 (6) ◽

pp. 2020-2029 ◽

Cited By ~ 64

Author(s):

Amaresh Das ◽

Radu Silaghi-Dumitrescu ◽

Lars G. Ljungdahl ◽

Donald M. Kurtz

Keyword(s):

Oxidative Stress ◽

Growth Conditions ◽

Strictly Anaerobic ◽

Paramagnetic Resonance ◽

Cysteine Synthase ◽

Moorella Thermoacetica ◽

Genes Encoding ◽

Uptake Activity ◽

Acetogenic Bacterium ◽

Cytochrome Bd Oxidase

ABSTRACT The gram-positive, thermophilic, acetogenic bacterium Moorella thermoacetica can reduce CO2 to acetate via the Wood-Ljungdahl (acetyl coenzyme A synthesis) pathway. This report demonstrates that, despite its classification as a strict anaerobe, M. thermoacetica contains a membrane-bound cytochrome bd oxidase that can catalyze reduction of low levels of dioxygen. Whole-cell suspensions of M. thermoacetica had significant endogenous O2 uptake activity, and this activity was increased in the presence of methanol or CO, which are substrates in the Wood-Ljungdahl pathway. Cyanide and azide strongly (∼70%) inhibited both the endogenous and CO/methanol-dependent O2 uptake. UV-visible light absorption and electron paramagnetic resonance spectra of n-dodecyl-β-maltoside extracts of M. thermoacetica membranes showed the presence of a cytochrome bd oxidase complex containing cytochrome b 561, cytochrome b 595, and cytochrome d (chlorin). Subunits I and II of the bd oxidase were identified by N-terminal amino acid sequencing. The M. thermoacetica cytochrome bd oxidase exhibited cyanide-sensitive quinol oxidase activity. The M. thermoacetica cytochrome bd (cyd) operon consists of four genes, encoding subunits I and II along with two ABC-type transporter proteins, homologs of which in other bacteria are required for assembly of the bd complex. The level of this cyd operon transcript was significantly increased when M. thermoacetica was grown in the absence of added reducing agent (cysteine + H2S). Expression of a 35-kDa cytosolic protein, identified as a cysteine synthase (CysK), was also induced by the nonreducing growth conditions. The combined evidence indicates that cytochrome bd oxidase and cysteine synthase protect against oxidative stress and contribute to the limited dioxygen tolerance of M. thermoacetica.

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Rubrerythrin and Rubredoxin Oxidoreductase inDesulfovibrio vulgaris: a Novel Oxidative Stress Protection System

Journal of Bacteriology ◽

10.1128/jb.183.1.101-108.2001 ◽

2001 ◽

Vol 183 (1) ◽

pp. 101-108 ◽

Cited By ~ 156

Author(s):

Heather L. Lumppio ◽

Neeta V. Shenvi ◽

Anne O. Summers ◽

Gerrit Voordouw ◽

Donald M. Kurtz

Keyword(s):

Oxidative Stress ◽

Protection System ◽

Superoxide Reductase ◽

Desulfovibrio Vulgaris ◽

Sod Activity ◽

E Coli ◽

Anaerobic Microorganisms ◽

Stress Protection ◽

Cell Extracts ◽

Oxidative Stress Protection

ABSTRACT Evidence is presented for an alternative to the superoxide dismutase (SOD)-catalase oxidative stress defense system inDesulfovibrio vulgaris (strain Hildenborough). This alternative system consists of the nonheme iron proteins, rubrerythrin (Rbr) and rubredoxin oxidoreductase (Rbo), the product of therbo gene (also called desulfoferrodoxin). A Δrbo strain of D. vulgaris was found to be more sensitive to internal superoxide exposure than was the wild type. Unlike Rbo, expression of plasmid-borne Rbr failed to restore the aerobic growth of a SOD-deficient strain of Escherichia coli. Conversely, plasmid-borne expression of two different Rbrs from D. vulgaris increased the viability of a catalase-deficient strain of E. coli that had been exposed to hydrogen peroxide whereas Rbo actually decreased the viability. A previously undescribed D. vulgaris gene was found to encode a protein having 50% sequence identity to that of E. coliFe-SOD. This gene also encoded an extended N-terminal sequence with high homologies to export signal peptides of periplasmic redox proteins. The SOD activity of D. vulgaris is not affected by the absence of Rbo and is concentrated in the periplasmic fraction of cell extracts. These results are consistent with a superoxide reductase rather than SOD activity of Rbo and with a peroxidase activity of Rbr. A joint role for Rbo and Rbr as a novel cytoplasmic oxidative stress protection system in D. vulgaris and other anaerobic microorganisms is proposed.

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Pathway for H2O2 and O2 detoxification in Clostridium acetobutylicum

Microbiology ◽

10.1099/mic.0.022756-0 ◽

2009 ◽

Vol 155 (1) ◽

pp. 16-24 ◽

Cited By ~ 66

Author(s):

Oliver Riebe ◽

Ralf-Jörg Fischer ◽

David A. Wampler ◽

Donald M. Kurtz ◽

Hubert Bahl

Keyword(s):

Oxidative Stress ◽

Electron Transfer ◽

Clostridium Acetobutylicum ◽

Consumption Rate ◽

Nadh Oxidase ◽

Strictly Anaerobic ◽

Nadh Peroxidase ◽

Overexpressing Strain

An unusual non-haem diiron protein, reverse rubrerythrin (revRbr), is known to be massively upregulated in response to oxidative stress in the strictly anaerobic bacterium Clostridium acetobutylicum. In the present study both in vivo and in vitro results demonstrate an H2O2 and O2 detoxification pathway in C. acetobutylicum involving revRbr, rubredoxin (Rd) and NADH : rubredoxin oxidoreductase (NROR). RevRbr exhibited both NADH peroxidase (NADH : H2O2 oxidoreductase) and NADH oxidase (NADH : O2 oxidoreductase) activities in in vitro assays using NROR as the electron-transfer intermediary from NADH to revRbr. Rd increased the NADH consumption rate by serving as an intermediary electron-transfer shuttle between NROR and revRbr. While H2O2 was found to be the preferred substrate for revRbr, its relative oxidase activity was found to be significantly higher than that reported for other Rbrs. A revRbr-overexpressing strain of C. acetobutylicum showed significantly increased tolerance to H2O2 and O2 exposure. RevRbr thus appears to protect C. acetobutylicum against oxidative stress by functioning as the terminal component of an NADH peroxidase and NADH oxidase.

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33 The Study of Strictly Anaerobic Microorganisms

Methods in Microbiology ◽

10.1016/s0580-9517(08)70036-9 ◽

2006 ◽

pp. 757-782 ◽

Cited By ~ 1

Author(s):

Kevin R Sowers ◽

Joy EM Watts

Keyword(s):

Strictly Anaerobic ◽

Anaerobic Microorganisms

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Selenocysteine, Pyrrolysine, and the Unique Energy Metabolism of Methanogenic Archaea

Archaea ◽

10.1155/2010/453642 ◽

2010 ◽

Vol 2010 ◽

pp. 1-14 ◽

Cited By ~ 38

Author(s):

Michael Rother ◽

Joseph A. Krzycki

Keyword(s):

Energy Metabolism ◽

Energy Conservation ◽

Methanogenic Archaea ◽

Strictly Anaerobic ◽

Related Research ◽

Stop Codons ◽

Anaerobic Microorganisms ◽

Two Systems ◽

Recent Developments

Methanogenic archaea are a group of strictly anaerobic microorganisms characterized by their strict dependence on the process of methanogenesis for energy conservation. Among the archaea, they are also the only known group synthesizing proteins containing selenocysteine or pyrrolysine. All but one of the known archaeal pyrrolysine-containing and all but two of the confirmed archaeal selenocysteine-containing protein are involved in methanogenesis. Synthesis of these proteins proceeds through suppression of translational stop codons but otherwise the two systems are fundamentally different. This paper highlights these differences and summarizes the recent developments in selenocysteine- and pyrrolysine-related research on archaea and aims to put this knowledge into the context of their unique energy metabolism.

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Anaerobic microorganisms and bioremediation of organohalide pollution

Microbiology Australia ◽

10.1071/ma15044 ◽

2015 ◽

Vol 36 (3) ◽

pp. 125 ◽

Cited By ~ 1

Author(s):

Matthew Lee ◽

Chris Marquis ◽

Bat-Erdene Judger ◽

Mike Manefield

Keyword(s):

Electron Acceptor ◽

Strictly Anaerobic ◽

Terminal Electron Acceptor ◽

Anaerobic Microorganisms ◽

Naturally Occurring ◽

Subsurface Environments ◽

Industrialised Countries

Organohalide pollution of subsurface environments is ubiquitous across all industrialised countries. Fortunately, strictly anaerobic microorganisms exist that have evolved using naturally occurring organohalides as their terminal electron acceptor. These unusual organisms are now being utilised to clean anthropogenic organohalide pollution.

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Identification of the Clostridium perfringens Genes Involved in the Adaptive Response to Oxidative Stress

Journal of Bacteriology ◽

10.1128/jb.184.9.2333-2343.2002 ◽

2002 ◽

Vol 184 (9) ◽

pp. 2333-2343 ◽

Cited By ~ 62

Author(s):

V. Briolat ◽

G. Reysset

Keyword(s):

Oxidative Stress ◽

Stress Response ◽

Clostridium Perfringens ◽

Adaptive Response ◽

Insertional Mutagenesis ◽

Redox Balance ◽

Single Copy ◽

Oxidative Stress Response ◽

Strictly Anaerobic ◽

Gene Encoding

ABSTRACT Clostridium perfringens is a ubiquitous gram-positive pathogen that is present in the air, soil, animals, and humans. Although C. perfringens is strictly anaerobic, vegetative and stationary cells can survive in a growth-arrested stage in the presence of oxygen and/or low concentrations of superoxide and hydroxyl radicals. Indeed, it possesses an adaptive response to oxidative stress, which can be activated in both aerobic and anaerobic conditions. To identify the genes involved in this oxidative stress response, C. perfringens strain 13 mutants were generated by Tn916 insertional mutagenesis and screened for resistance or sensitivity to various oxidative stresses. Three of the 12 sensitive mutants examined harbored an independently inserted single copy of the transposon in the same operon as two genes orthologous to the ydaD and ycdF genes of Bacillus subtilis, which encode a putative NADPH dehydrogenase. Complementation experiments and knockout experiments demonstrated that these genes are both required for efficient resistance to oxidative stress in C. perfringens and are probably responsible for the production of NADPH, which is required for maintenance of the intracellular redox balance in growth-arrested cells. Other Tn916 disrupted genes were also shown to play important roles in the oxidative stress response. This is the first time that some of these genes (e.g., a gene encoding an ATP-dependent RNA helicase, the β-glucuronidase gene, and the gene encoding the atypical iron sulfur prismane protein) have been shown to be involved in the oxidative response.

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