Oxygen Sensitivity of Methanogenic Bacteria

Kiener, Andreas; Leisinger, Thomas

doi:10.1016/s0723-2020(83)80017-4

Cited by 203 publications

(123 citation statements)

References 12 publications

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“…In contrast, late evolving methanogens, such as Methanobacteria and Methanomicrobia, were devoid of DFTR homologs, carried 1-9 Trxs, 1-3 NTRs, and 0 -3 FTRs (9,20). The Methanococci are more sensitive to oxygen than the late evolving methanogens (72). Thus, DFTR seems to be part of the simpler Trx systems that exist in more fastidious and phylogenetically and deeply rooted methanogens inhabiting niches presenting early Earth type reduced environment with an abundant supply of hydrogen, and a transition to the NTR and FTR systems brought about more tolerance to oxygen exposure or it is a consequence of an adaptation to niches that experience occasional oxygen exposure and/or less reduced conditions.…”

Section: Discussionmentioning

confidence: 97%

A Novel F420-dependent Thioredoxin Reductase Gated by Low Potential FAD

Susanti¹,

Loganathan²,

Mukhopadhyay

2016

Journal of Biological Chemistry

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A recent report suggested that the thioredoxin-dependent metabolic regulation, which is widespread in all domains of life, existed in methanogenic archaea about 3.5 billion years ago. We now show that the respective electron delivery enzyme (thioredoxin reductase, TrxR), although structurally similar to flavincontaining NADPH-dependent TrxRs (NTR), lacked an NADPH-binding site and was dependent on reduced coenzyme F 420 (F 420 H 2 ), a stronger reductant with a mid-point redox potential (E 0 ) of ؊360 mV; E 0 of NAD(P)H is ؊320 mV. Because F 420 is a deazaflavin, this enzyme was named deazaflavin-dependent flavin-containing thioredoxin reductase (DFTR). It transferred electrons from F 420 H 2 to thioredoxin via proteinbound flavin; K m values for thioredoxin and F 420 H 2 were 6.3 and 28.6 M, respectively. The E 0 of DFTR-bound flavin was approximately ؊389 mV, making electron transfer from NAD(P)H or F 420 H 2 to flavin endergonic. However, under high partial pressures of hydrogen prevailing on early Earth and present day deep-sea volcanoes, the potential for the F 420 /F 420 H 2 pair could be as low as ؊425 mV, making DFTR efficient. The presence of DFTR exclusively in ancient methanogens and mostly in the early Earth environment of deep-sea volcanoes and DFTR's characteristics suggest that the enzyme developed on early Earth and gave rise to NTR. A phylogenetic analysis revealed six more novel-type TrxR groups and suggested that the broader flavin-containing disulfide oxidoreductase family is more diverse than previously considered. The unprecedented structural similarities between an F 420 -dependent enzyme (DFTR) and an NADPH-dependent enzyme (NTR) brought new thoughts to investigations on F 420 systems involved in microbial pathogenesis and antibiotic production.

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Section: Discussionmentioning

confidence: 97%

A Novel F420-dependent Thioredoxin Reductase Gated by Low Potential FAD

Susanti¹,

Loganathan²,

Mukhopadhyay

2016

Journal of Biological Chemistry

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“…Methanobrevibacter arboriphilus and Methanobacterium thermoautotrophicum were shown to maintain their vitality under aerobic con ditions for several hours [1]. In the case of Methanosarcina barkeri, this period was more than 24 h, this being due to the formation of cell clots [1]. To provide defense against the toxic effects of prod ucts of incomplete reduction of oxygen (H 2 O 2 , OH • , and O 2 ), many strict anaerobes as well as aerobic organisms contain antioxidant enzymes.…”

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confidence: 99%

“…However, in spite of their inability to produce CH 4 in the presence of oxygen, they are capable of existing in the presence of oxygen for a short time. Methanobrevibacter arboriphilus and Methanobacterium thermoautotrophicum were shown to maintain their vitality under aerobic con ditions for several hours [1]. In the case of Methanosarcina barkeri, this period was more than 24 h, this being due to the formation of cell clots [1].…”

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confidence: 99%

Purification and characterization of Fe-containing superoxide dismutase from Methanobrevibacter arboriphilus strain AZ

Bryukhanov

Nesatyy

Netrusov

2006

Biochemistry (Moscow)

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Methanogenic Archaea are ancient microorganisms that retain many features of their ancestors and exist under extreme conditions of severe anaerobiosis. However, in spite of their inability to produce CH 4 in the presence of oxygen, they are capable of existing in the presence of oxygen for a short time. Methanobrevibacter arboriphilus and Methanobacterium thermoautotrophicum were shown to maintain their vitality under aerobic con ditions for several hours [1]. In the case of Methanosarcina barkeri, this period was more than 24 h, this being due to the formation of cell clots [1]. To provide defense against the toxic effects of prod ucts of incomplete reduction of oxygen (H 2 O 2 , OH • , and O 2 ), many strict anaerobes as well as aerobic organisms contain antioxidant enzymes. The most important of these are catalase and superoxide dismutase (SOD). SOD removes free superoxide radicals that arise during the one electron reduction of O 2 , catalyzing the dismu tation reaction of O 2 , yielding H 2 O 2 and O 2 . Hydrogen peroxide acts as a reductant of the enzyme at low con centrations and as a reversible inactivator at high con centrations. The reaction mechanism includes alternat ing reduction and reoxidation of the metal in the active site of the SOD during consecutive interactions with O 2 [8].The detection of SOD in obligate anaerobes raised a question concerning its function and origin in these organisms. Apparently, the main physiological role of SOD in anaerobic microorganisms as well as in aerobes is the prevention of cell damage caused by oxygen by neu tralizing superoxide radicals. The latter may arise due to a transient exposure of the anaerobic cells to the air during the reaction of O 2 with reduced flavins, catecholamines, quinones, iron and sulfur containing proteins, as well as under the action of mutagens and UV radiation [9]. It has been shown that strictly anaerobic microorganisms pos sessing significant SOD activity exhibit moderate or high ISSN 0006 2979, Biochemistry (Moscow), 2006, Vol. 71, No. 4, pp. 441 447. © Pleiades Publishing, Inc., 2006. Original Russian Text © A. L. Brioukhanov, V. J. Nesatyy, A. I. Netrusov, 2006, published in Biokhimiya, 2006 441 * To whom correspondence should be addressed. Abstract-Superoxide dismutase (SOD) was purified from cells of the strict anaerobic methanogenic archaeon Methanobrevibacter arboriphilus strain AZ. The four step purification procedure resulted in enzyme with specific activity of 3970 units/mg and yield of 22%. It was shown that the SOD is a Fe containing homotetramer composed of subunits of 21.2 kD each. Sodium azide (13.5 mM), unlike KCN, inhibits the activity of the SOD. Hydrogen peroxide (0.5 mM) inac tivates the enzyme, which is consistent with the properties of the known Fe containing SODs from methanogenic Archaea. Purification and Characterization of Fe Containing

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“…The effect of limited air supplied on the archaeal community structure and specific methanogenic activity (SMA) 3.3.1. The archaeal community structure change under microaerobic condition Methanogenic microorganisms are conventionally thought to be strictly anaerobic, tiny oxygen exposed may be lethal to the activity of methanogenic microorganisms [11,36]. However, it was reported methanogenic microorganisms belong to Methanobacterium and Methanosarcina all showed tolerance to limited oxygen [11,12].…”

Section: Tablementioning

confidence: 99%

Effect of Different Mixed Microflora on the Performance of Thermophilic Microaerobic Pretreatment

Shi

Meng

et al. 2016

Energy Fuels

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h i g h l i g h t sThe effect of limited oxygen daily supplied on the AD of corn straw was studied. Daily oxygen supplied could obviously improve the AD performance of corn straw. Specific methanogenic activity under microaerobic condition improved slightly. The microbial community structure shift could explain the better AD performance. a r t i c l e i n f o b s t r a c tConventionally, oxygen is considered as inhibit factor of anaerobic digestion (AD). However, recent studies have demonstrated that AD performance could be enhanced by introducing limited amounts of oxygen (or air) directly into the anaerobic digester or during pretreatment step. In this study, impacts of microaeration on the anaerobic digestion of corn straw and the microbial community structure were investigated. Results showed that limited air introduced into fermentation system could improve the methane yield of corn straw. Maximum cumulative methane yield of 216.8 ml/g VS substrate and maximum VS removal efficiency of 54.3% were simultaneously obtained under microaerobic condition with the air load of 12.5 ml/L R per day, which were 16.5% and 10.3% higher than those of sample under anaerobic condition, respectively. Compared to anaerobic condition, the relative abundances of phylum Firmicutes, class Clostridia and order Clostridiales, which associated with hydrolysis process of AD were raised under microaerobic condition. In addition, the relative abundances of oxytolerant Methanosarcina and Methanobacterium were both doubled under microaerobic condition. Accordingly, specific methanogenic activity (SMA) under microaerobic condition improved slightly. The microbial community shift might be the reason for improved AD performance under microaerobic condition.

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Oxygen Sensitivity of Methanogenic Bacteria

Cited by 203 publications

References 12 publications

A Novel F420-dependent Thioredoxin Reductase Gated by Low Potential FAD

A Novel F420-dependent Thioredoxin Reductase Gated by Low Potential FAD

Purification and characterization of Fe-containing superoxide dismutase from Methanobrevibacter arboriphilus strain AZ

Effect of Different Mixed Microflora on the Performance of Thermophilic Microaerobic Pretreatment

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