33 The Study of Strictly Anaerobic Microorganisms

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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Aetiology of caprine footrot in Extremadura region, Spain

Acta Veterinaria Hungarica ◽

10.1556/avet.54.2006.3.2 ◽

2006 ◽

Vol 54 (3) ◽

pp. 313-320 ◽

Cited By ~ 3

Author(s):

Angela Lacombe-Antoneli ◽

S. Píriz ◽

S. Vadillo

Keyword(s):

Virulence Factors ◽

Fusobacterium Necrophorum ◽

Minor Importance ◽

Strictly Anaerobic ◽

Anaerobic Microorganisms ◽

Dichelobacter Nodosus ◽

Prevotella Melaninogenica

The present study reports on the location of major foci of footrot in goats in the Extremadura region of Spain by the determination of locally occurring strictly anaerobic microorganisms involved in the pathogenesis and development of this disease. The most commonly isolated microorganisms belonged to the genera Dichelobacter, Fusobacterium, Porphyromonas and Prevotella; these were found in conjunction with other species of minor importance. The species most frequently isolated were Fusobacterium necrophorum (40%), Dichelobacter nodosus (31.7%), Porphyromonas asaccharolytica (21.1%) and Prevotella melaninogenica (12.9%). Virulence factors identified in the isolated microorganisms included haemolysins, elastases and lecithinases, which enabled the organisms involved to initiate and/or aggravate the disease. Serotyping was performed for Dichelobacter nodosus isolates, since this species is responsible for triggering the process of infection. A and C were the most frequently isolated serovarieties (representing 40.7% and 25.9% of the cases, respectively).

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Monitoring of dry anaerobic fermentation in experimental facility with use of biofilm reactor

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis ◽

10.11118/actaun201159060343 ◽

2011 ◽

Vol 59 (6) ◽

pp. 343-354 ◽

Cited By ~ 1

Author(s):

Milan Šinkora ◽

Miroslav Havlíček

Keyword(s):

Anaerobic Fermentation ◽

Liquid Solution ◽

Biofilm Reactor ◽

Bacterial Biofilm ◽

Biologically Active ◽

Strictly Anaerobic ◽

Anaerobic Microorganisms ◽

Active Liquid ◽

Micro Organisms ◽

Dry Fermentation

Anaerobic fermentation is a process in which almost any organic mass may be transformed into an energetically rich biogas and a fermentation residue. Only strictly anaerobic microorganisms enter into the process; thus the process may take place only in a hermetically sealed environment. With regard to the world wide situation, where the increase in the proportion of energy from sustainable sources is in demand, anaerobic fermentation offers the possibility of transforming farm waste, farm products and municipality waste of biological character into electricity. This electricity may subsequently become an interesting source of income. The system may be proposed to agricultural companies as well as to municipality corporations. The process of fermentation may be carried out as dry fermentation or as liquid fermentation. Dry fermentation, working with materials where the percentage of dry matter exceeds 15 %, is the topic of this paper. This method has been frequently discussed as a method of processing organic material without waste water and thus the volume of material as well as the size of the biogas plant considerably decreases. To enable progress in the process, it is necessary to use a biologically active liquid solution containing the essential micro-organisms, often termed “percolate”. To activate a fresh substrate, fermented material adulterant containing cultivated microorganisms from previous processes is used; the ratio in which it is used is approximately one third to one fifth. “Percolate strategy” is another phrase used for sustaining the anaerobic fermentation; material is sprinkled on the percolate in the precisely defined cycles. In addition, the biologically active liquid solution contains organic substances washed out from the fermented material. With regard to its amount, this paper has become an impulse for the research in the amount of biogas which may be subsequently produced from the percolate in the so-called biofilm reactor. An external reactor with a cultivated bacterial biofilm on an immovable carrier with the percolate flowing through it has been constructed in laboratory conditions for this purpose. The choice of suitable percolate strategy (this means the frequency of sprinkling) and the amount of percolate directly influences the process of anaerobic fermentation.

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Reductive transformation of tetrachloroethylene to ethylene and ethane by an anaerobic filter

Water Science & Technology ◽

10.2166/wst.1997.0583 ◽

1997 ◽

Vol 36 (6-7) ◽

pp. 125-132 ◽

Cited By ~ 3

Author(s):

Toshiya Komatsu ◽

Jun Shinmyo ◽

Kiyoshi Momonoi

Keyword(s):

Electron Donor ◽

Laboratory Scale ◽

Groundwater Contaminants ◽

Reductive Transformation ◽

Filter System ◽

Anaerobic Filter ◽

Anaerobic Microorganisms ◽

Chlorinated Ethylenes ◽

Start Up ◽

Low Concentrations

Tetrachloroethylene (PCE) is one of the most common groundwater contaminants in Japan. PCE can be completely dechlorinated to ethylene (ETY) and ethane (ETA) by anaerobic microorganisms in the presence of a suitable electron donor. This study was conducted to examine the feasibility of using an anaerobic filter for the degradation of PCE in a bioremediation process. Laboratory-scale anaerobic filters were operated at 25°C using ethanol as the electron donor. Rapid start-up of the reactors was achieved by using anaerobic completely PCE-dechlorinating enrichment cultures as the inoculum. During the continuous operating periods, low concentrations (2.8 mg/L) of PCE were almost completely dechlorinated to ETY and ETA at hydraulic retention times of 49-15 hours with 100 mgCOD/L of ethanol. PCE concentrations as high as 80 mg/L was dechlorinated to ETY with a relatively low supply (200 mgCOD/L) of ethanol. Results of this study suggest that the anaerobic filter system is a feasible bioremediation process for the cleanup of groundwater which is contaminated by chlorinated ethylenes.

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Special Issue “Anaerobes in Biogeochemical Cycles”

Microorganisms ◽

10.3390/microorganisms9010023 ◽

2020 ◽

Vol 9 (1) ◽

pp. 23

Author(s):

Caroline M. Plugge ◽

Diana Z. Sousa

Keyword(s):

Essential Role ◽

Biogeochemical Cycles ◽

Special Issue ◽

Anaerobic Microorganisms ◽

Global Biogeochemical Cycles

Anaerobic microorganisms, Bacteria and Archaea, have an essential role in global biogeochemical cycles [...]

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Anoxygenic photo- and chemosynthesis of phototrophic sulfur bacteria from an alpine meromictic lake

FEMS Microbiology Ecology ◽

10.1093/femsec/fiab010 ◽

2021 ◽

Author(s):

Francesco Di Nezio ◽

Clarisse Beney ◽

Samuele Roman ◽

Francesco Danza ◽

Antoine Buetti-Dinh ◽

...

Keyword(s):

Carbon Fixation ◽

Meromictic Lake ◽

Purple Sulfur Bacterium ◽

Phototrophic Sulfur Bacteria ◽

Anaerobic Microorganisms ◽

Sulfur Bacteria ◽

Pure Cultures ◽

Chlorobium Phaeobacteroides ◽

Anoxic Environment ◽

Dark Carbon Fixation

Abstract Meromictic lakes are interesting ecosystems to study anaerobic microorganisms due their permanent stratification allowing the formation of a stable anoxic environment. The crenogenic meromictic Lake Cadagno harbors an important community of anoxygenic phototrophic sulfur bacteria responsible for almost half of its total productivity. Besides their ability to fix CO2 through photosynthesis, these microorganisms also showed high rates of dark carbon fixation via chemosyntesis. Here, we grew in pure cultures three populations of anoxygenic phototrophic sulfur bacteria previously isolated from the lake, accounting for 72.8% of the total microbial community, and exibiting different phenotypes: 1) the motile, large-celled purple sulfur bacterium (PSB) Chromatium okenii, 2) the small-celled PSB Thiodictyon syntrophicum, and 3) the green sulfur bacterium (GSB) Chlorobium phaeobacteroides. We measured their ability to fix CO2 through photo- and chemo-synthesis, both in situ in the lake and in laboratory under different incubation conditions. We also evaluated the efficiency and velocity of H2S photo-oxidation, an important reaction in the anoxygenic photosynthesis process. Our results confirm that phototrophic sulfur bacteria strongly fix CO2 in the presence of light and that oxygen increases chemosynthesis at night, in laboratory conditions. Moreover, substancial differences were displayed between the three selected populations in terms of activity and abundance.

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