Methanobrevibacter smithii are archaea that live in the intestine, oral flora, and genital tract of mammals. They are so-called methanogens that metabolize carbon dioxide and hydrogen to water and methane, supporting healthy colonization of the intestine, mouth, and genital tract. The absence of Methanobrevibacter smithii in the colon is now associated with obesity.
What are methanobrevibacter smithii?
Methanobrevibacter smithii are archaea that live in the intestines, oral flora, and genital tract of mammals. They are so-called methanogens. Archaebacteria are one of three domains of cellular organisms, along with bacteria and eukaryotes. Archaea are single-celled organisms whose DNA is arranged in small volumes. They belong to the prokaryotes. Archaea do not contain cell organelles. The human body naturally contains a certain number of unicellular organisms and is thus the natural habitat of various bacterial colonies. For example, different protozoa live in the human intestine and perform various tasks related to digestive processes. One of the most important intestinal bacteria is Methanobrevibacter smithii. This is an archaebacterium that colonizes not only the intestines of many mammals but also the vagina and the oral flora of humans. The bacterium belongs to the hydrogenotrophic methane producers whose energy metabolism produces methane. Methane belongs to the group of alkanes and is formed within an organism in the intestinal tract from enzymatically split food. Methane-forming microorganisms such as Methanobrevibacter smithii are actually incorrectly referred to as bacteria. Bacteria and archaea were originally assigned to a common taxon. Since the 1990s, however, bacteria and archaea have tended to be treated as two distinct taxa, with methanogenesis being carried out exclusively by archaea. Thus, all methane producers belong to the Archaea and thus to the Euryarchaeota.
Occurrence, distribution, and characteristics
The archaea Methanobrevibacter smithii are organisms that grow in oxygen-free habitats. This characteristic is also known as obligate anaerobes. This form of anaerobia distinguishes archaea from organisms that can live facultatively in oxic conditions. The intestinal inhabitants are fluorescent and methanogenic. They metabolize hydrogen and carbon dioxide in the gut flora and dental flora to methane and water with energy gain. In this context, the archaea are also referred to as hydrogenotrophic methanogens. Hydrogen and carbon are produced in the gut and dental flora of mammals mainly due to the metabolic processes of other microorganisms. For methanogens, the release of energy during methanogenesis is a vital process. Accordingly, methanogenesis serves as an energy source for them. Consequently, the archaea are not parasites: they do not grow at the expense of host organisms, but coexist with them in a mutually beneficial relationship. Methanobrevibacter smithii are methanogens that convert carbon dioxide and hydrogen to water and methane. Formic acid conversion may also play a role in methanol production. All methanogens prefer to live at ideal temperatures between zero and 70 degrees Celsius. They are less able to cope with sub-zero temperatures, and temperatures higher than 90 degrees also have a lethal effect on them. Temperatures above 50 degrees, on the other hand, make the methane formers particularly efficient. The ideal environment for the archaea is pH-neutral or slightly alkaline and optimally consists of 50 percent water. The habitat of methane formers is not exclusively the human or animal body. Many formers also occur in aquatic sediments, water-saturated soils or manure, as they also find nitrogen compounds, mineral elements and trace elements to survive in these habitats. The microorganisms are inhibited by organic acids, oxygen and disinfectants. In the human intestine, they are found primarily within the large intestine section. Ultimately, Methanobrevibacter smithii are part of the anaerobic food chain and represent its final stage. The metabolic conversions that occur there lead to the formation of methane.
Significance and function
Methanobrevibacter smithii perform vital tasks in the human body and represent a kind of waste disposal system.The waste recyclers clean up in the colon and within the dental flora by recycling the waste products of other microorganisms. These waste products are primarily hydrogen molecules, from which colleagues the archaea produce methane. In this context, the microorganisms play a crucial role in, among other things, flatulence. The activity of Methanobrevibacter smithii supports the settlement of other intestinal and dental bacteria. For both dental flora and intestinal flora, methanobrevibacters are indispensable elements that contribute significantly to the functioning of the whole system. According to new scientific findings, not all people carry the archaea in their intestines.
Diseases and ailments
In about 15 percent of the population, Methanobrevibacter smithii do not colonize the intestinal flora. Scientists believe that when the bacteria are absent, fewer beneficial bacteria settle in the gut. This would mean that people without the methane-forming gut inhabitants have poorer, less functional digestion than those with the archaea. One scientific research topic in this context is obesity. Some scientists are currently speculating on the extent to which the absence of Methanobrevibacter smithii might promote obesity and related conditions. Similarly, in the dental flora, the absence of the archaea could lead to a general reduction in beneficial bacteria, thus favoring dental diseases attributable to poor dental flora. With regard to obesity, science has already reached initial results by means of animal experiments. In one study, Washington University colonized the intestines of mice with the same intestinal bacteria found in the human gut. Certain individuals did not receive Methanobrevibacter smithii in the experiment, while others were colonized with Methanobrevibacter smithii. At the end of the study, the experimental animals without Methanobrevibacter smithii were significantly fatter than the individuals with the microorganisms.
