15+ Methanogenic Bacteria Examples: Detailed Explanations and Images

With a few methanogenic bacteria examples we will know about methanogens which are a group of bacteria that produce methane as a byproduct of their anaerobic metabolism.

Methanogenic bacteria example as prokaryotic organisms that belong to the phylum Euryarchaeota under domain Archaea. They are obligatory anaerobes and obtain energy by breaking down CO₂, hydrogen, acetate, formate, methanol etc. into methane and carbon dioxide.

A few Methanogenic bacteria examples,

They are a diverse group of organism which can survive in various extreme habitats; like hydrothermal vents, geothermal vents, anaerobic digesters, bogs etc. They are also found in decomposing organic matters, rumen of herbivorous animals, intestine of various mammals, guts of insects etc.

Process of methane formation:

These bacteria are very sensitive to oxygen even at a trace level and susceptible to oxygen stress by prolonged exposure. They break down CO₂ into Methane in presence of hydrogen,

CO₂ + 4H₂ —> CH₄ + 2H₂O

Methanobacterium bryantii–

Methanobacterium oryzae–

• Phylum: Euryarchaeota
• Class: Methanobacteria
• Order: Methanobacteriales
• Family: Methanobacteriaceae
• Genus: Methanobacterium
• Species: oryzae

This rod-shaped, non-motile bacterium was first isolated from paddy field of Philippines. They grow at a temperature of 40^oC and a neutral pH of 7.

Methanobrevibacter acididurans–

• Phylum: Euryarchaeota
• Class: Methanobacteria
• Order: Methanobacteriales
• Family: Methanobacteriaceae
• Genus: Methanobrevibacter
• Species: acididurans

These hydrogenotrophic methanogens are acid tolerant and are usually found in gut of larger animals such as mice, termites etc. These organisms can grow optimally at a temperature of 35^oC to 37^oC and 6 pH. They don’t have peptidoglycan as their cell wall component, rather are made of pseudomurein. Under acidic condition these bacteria shows better Methanogenic capacity than other bacteria of same order and decrease accumulation of volatile fat causing obesity.

Methanosphaera cuniculi–

• Phylum: Euryarchaeota
• Class: Methanobacteria
• Order: Methanobacteriales
• Family: Methanobacteriaceae
• Genus: Methanosphaera
• Species: cuniculi

These gram-positive, non-motile, spherical or oval methanogens are commonly found in ruminant gut because they prefer low hydrogen or methane producing host. They were first isolated from gut of rabbit and have an optimal growth temperature of 30-40^oC and optimum pH is 6.8.

Methanothermobacter thermoflexus–

• Phylum: Euryarchaeota
• Class: Methanobacteria
• Order: Methanobacteriales
• Family: Methanobacteriaceae
• Genus: Methanothermobacter
• Species: thermoflexus

These rod-shaped, filamentous, gram positive methanogens are moderate thermophiles and have an optimal temperature of 55-60^oC and a neutral pH value of 7. It was first isolated from digester sludge of methacrylate wastewater in Russia.

Methanothermus sociabilis–

• Phylum: Euryarchaeota
• Class: Methanobacteria
• Order: Methanobacteriales
• Family: Methanothermaceae
• Genus: Methanothermus
• Species: sociabilis

Small, rod-shaped, gram positive, motile bacteria generally occur singly or form a short chain or cluster. Their cell wall is made of pseudomurein with an outer layer of protein S. They are highly thermophilic and can survive up to 97^oC.

Methanococcus aeolicus–

• Phylum: Euryarchaeota
• Class: Methanococci
• Order: Methanococcales
• Family: Methanococcaceae
• Genus: Methanococcus
• Species: aeolicus

These small cocci-shaped methanogens are isolated from marine sediment and is the first archaeal genome to be sequenced. They are gram negative, non-motile bacteria that have their cell wall made of protein.

Methanothermococcus okinawensis–

• Phylum: Euryarchaeota
• Class: Methanococci
• Order: Methanococcales
• Family: Methanococcaceae
• Genus: Methanothermococcus
• Species: okinawensis

These motile, irregular cocci, thermophilic archaeon was first isolated from a deep sea vent chimney at Iheya ridge in Okinawa, Japan. They have an optimum pH of 6.7 and optimum temperature of 60-65^oC.

Methanocaldococcus indicus–

• Phylum: Euryarchaeota
• Class: Methanococci
• Order: Methanococcales
• Family: Methanocaldococcaceae
• Genus: Methanocaldococcus
• Species: indicus

They are motile, coccoid methanogens; first found in deep sea hydrothermal vent in Central Indian Ridge in international waters. It can grow from 50^oC to 85^oC temperature and around 6.5 pH.

Methanotorris igneus–

• Phylum: Euryarchaeota
• Class: Methanococci
• Order: Methanococcales
• Family: Methanocaldococcaceae
• Genus: Methanotorris
• Species: igneus

Small, free living, hyperthermophilic methanogens first found in shallow submarine hydrothermal vent at Kolbeinsey ridge in Iceland.

Methanopyrus kandleri–

• Phylum: Euryarchaeota
• Class: Methanopyri
• Order: Methanopyrales
• Family: Methanopyraceae
• Genus: Methanopyrus
• Species: kandleri.

This rod shaped, hyperthermophilic methanogen is the only species of methanopyraceae family. They were first found surviving at a 2000m depth and 84-110^oC temperature at Gulf of California. They have their cell wall made of terpenoid lipids.

Methanocella arvoryzae–

• Phylum: Euryarchaeota
• Class: Methanomicrobia
• Order: Methanocellales
• Family: Methanocellaceae
• Genus: Methanocella
• Species: arvoryzae

These non-motile, rod shaped bacteria was first isolated from Italian rice field soil. They grow at an optimal 45^oC temperature and 7.1 pH. They mainly use acetate or formate as their primary energy source.

Methanogenium cariaci–

• Phylum: Euryarchaeota
• Class: Methanomicrobia
• Order: Methanomicrobiales
• Family: Methanomicrobiaceae
• Genus: Methanogenium
• Species: cariaci

These non-motile, gram negative, rod shaped methanogens are mesophilic, having an optimal temperature of 25^oC. First found in marine sediment of Cariaco trench in Venezuela.

Methanomicrobium mobile–

• Phylum: Euryarchaeota
• Class: Methanomicrobia
• Order: Methanomicrobiales
• Family: Methanomicrobiaceae
• Genus: Methanomicrobium
• Species: mobile.

Non-motile, slightly curved rod-shaped, gram negative methanogens are commonly found in ruminant stomach. They have an optimum growth temperature of 40^oC and 6.1 – 7.0 is optimal pH value.

Methanospirillum lacunae–

• Phylum: Euryarchaeota
• Class: Methanomicrobia
• Order: Methanomicrobiales
• Family: Methanospirillaceae
• Genus: Methanospirillum
• Species: lacunae

These motile, gram negative, curved rod or spiral shaped hydrogenotrophic methanogen are naturally found in wetland sediments and anaerobic sewage digesters.

Methanothrix soehngenii–

• Phylum: Euryarchaeota
• Class: Methanomicrobia
• Order: Methanosarcinales
• Genus: Methanothrix
• Species: soehngenii

They are non-motile, rod-shaped, mesophilic methanogens with an optimum growth temperature of 35^oC. These organisms were first isolated from anaerobic sewage sludge in Switzerland. They cannot process carbon dioxide like other methanogens and solely dependent on acetate as an energy source.

Methanosarcina barkeri–

• Phylum: Euryarchaeota
• Class: Methanomicrobia
• Order: Methanosarcinales
• Family: Methanosarcinaceae
• Genus: Methanosarcina
• Species: barkeri

These non-motile, gram positive, irregular coccoid methanogens grow into different sizes based on salt concentration of the medium. They were first isolated from aquatic sediments, digesters and in rumen of herbivores. They have a 4.8Mbp long nucleotides sequence and 3606 different proteins; which make the bacterium a model organism to study biotechnology and cell biology.

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