What Are Methanogens?

Methanogens are obligate anaerobic bacteria, belonging to the archaea domain, the wide archaea world, and the broad archaea. Methanogens are a group of archaea capable of anaerobic fermentation of inorganic or organic compounds into methane and carbon dioxide. Methanogens are important environmental microorganisms and play an important role in the carbon cycle of nature. So far, the sequencing of the genomes of five methanogens has been completed. Genomic information gives people a deeper understanding of the cell structure, evolution, metabolism, and environmental adaptability of methanogens. There are currently three known methane biosynthetic pathways. They start with acetic acid, methyl compounds, and hydrogen / carbon dioxide, and form methyl coenzyme M through different reaction pathways. Catalyzed by methyl coenzyme M reductase Eventually, methane is formed. ^[1] In 1974, Berger's Bacterial Identification Manual (eighth edition) classified it into 1 family, 3 genera, and 9 species. As of 1992, it has developed into 3 orders, 7 families, 19 genera and 70 species. As of 2009, it has developed into 5 orders, 12 families and 31 genera.

Methanogens are a group of archaea capable of anaerobic fermentation of inorganic or organic compounds into methane and carbon dioxide. Methanogens are important environmental microorganisms and play an important role in the carbon cycle of nature. ^[1]

Methanogens are strictly anaerobic microorganisms. Before the invention of strict anaerobic technology, the research on the isolation and cultivation of methanogens was slow. Methanosarcina barkeri and Methanobacterium formicium were the earliest isolated methanogens. In 1950, Hungate's anaerobic separation technology led to the rapid development of methanogens. The eighth edition of the 1974 Berger's Manual of Identification Bacteriology, based on the classification of methanogens, described it as an independent family. ^[2]

There are three ways of methane biosynthesis, including the biosynthesis process using acetic acid as the substrate, H ₂ / CO ₂ as the substrate, and methyl compounds as the substrate. Studies have shown that methane produced using acetate as a substrate accounts for 67% of methane in nature, while methane formed by H ₂ / CO ₂ conversion is less than 33% of methane in nature. Many unique enzymes participate in the methane generation process. These enzymes mainly include hydrogenase, coenzyme F420, formylmethylfuran, formyltetrahydromethylxanthine, and coenzyme M. By monitoring the unique enzymes in the methanogenesis process You can essentially understand the metabolism of methanogens. All three methane synthesis pathways eventually form methyl coenzyme M. Methyl coenzyme M is finally catalyzed by methyl coenzyme M reductase I (MCR I) and methyl coenzyme M reductase II (MCR II). ^[4]

1. Nutritional characteristics: There are five main types of energy and carbon sources of methane bacteria, namely H ₂ / CO ₂ , formic acid, methanol, methylamine and acetic acid.

2. Special coenzyme: F420: is an analog of flavin mononucleotide, a low molecular weight fluorescent compound with a molecular weight of 630. it is

Methanogens are obligate anaerobic bacteria, and operations such as isolation and culture need to be performed in special environments and using special techniques.

Classification of methanogen culture methods

Generally, the liquid deep culture method with paraffin or liquid paraffin added on the liquid surface, vacuum culture method, culture method of placing pyrogallic acid and potassium carbonate in a closed culture tube to remove oxygen (Berker), Hungate Anaerobic tube method, Hungate's anaerobic liquid culture method, Balch's anaerobic liquid culture pressurization method, etc.

Introduction to specific methods of methanogens

The best currently is the anaerobic glove box, which consists of four parts:

1. Closed transparent film box with gloves

2. Attached with two openable and evacuable metal air isolation boxes

3.Vacuum pump

4. Hydrogen and high purity nitrogen supply system

Using the anaerobic glove box can do many tasks, such as: packing anaerobic media, inverting plates, centrifuging anaerobic microorganisms to collect bacteria, separating and purifying oxygen-sensitive enzymes and coenzymes, performing electrophoresis, anaerobic biochemistry Response and genetic studies.