Bacteria and Methanogens in the Human Microbiome: a Review of Syntrophic Interactions

Small Intestinal Bacterial Overgrowth as Potential Therapeutic Target in Parkinson’s Disease

“…Methanogens are anaerobic microorganisms that produce methane as a by-product of the metabolization of simple substrates such as H 2 and carbon dioxide [ 75 , 81 , 90 ]. During the last five decades, different methanogen species have been identified in a variety of human biological specimens, such as periodontal, intestinal, colonic, or vaginal samples, feces, and even brain abscesses [ 90 ].…”

“…Methanogens are anaerobic microorganisms that produce methane as a by-product of the metabolization of simple substrates such as H 2 and carbon dioxide [ 75 , 81 , 90 ]. During the last five decades, different methanogen species have been identified in a variety of human biological specimens, such as periodontal, intestinal, colonic, or vaginal samples, feces, and even brain abscesses [ 90 ]. Despite initially being considered anaerobic bacteria, all currently known methanogens are Archaea species, minor and less-known constituents of the human microbiome, which are obligate bacteria cross-feeders and interact with bacteria in syntrophic ways [ 81 , 90 ].…”

“…During the last five decades, different methanogen species have been identified in a variety of human biological specimens, such as periodontal, intestinal, colonic, or vaginal samples, feces, and even brain abscesses [ 90 ]. Despite initially being considered anaerobic bacteria, all currently known methanogens are Archaea species, minor and less-known constituents of the human microbiome, which are obligate bacteria cross-feeders and interact with bacteria in syntrophic ways [ 81 , 90 ]. A methanogenic archaeome is present in protists, plants and animals, where it interacts with the hosts in a mutually beneficial fashion (i.e., symbiosis) [ 90 ].…”

“…Despite initially being considered anaerobic bacteria, all currently known methanogens are Archaea species, minor and less-known constituents of the human microbiome, which are obligate bacteria cross-feeders and interact with bacteria in syntrophic ways [ 81 , 90 ]. A methanogenic archaeome is present in protists, plants and animals, where it interacts with the hosts in a mutually beneficial fashion (i.e., symbiosis) [ 90 ]. The most prevalent species reported in humans are Methanobrevibacter smithii [ 91 ] and Ca.…”

“…The impact of methanogens on human health and disease is still largely unknown. Based on the current knowledge, methanogens are thought to have local and remote modulatory effects on the immune system and barrier role against pathogenic microorganisms in the digestive tract [ 90 ]. They seem to be able to interact with the immune system at the gastrointestinal system level, since exposure of dendritic cells to M. stadtmanae and M. smithii leads to release of proinflammatory cytokines, up-regulation of the cell-surface receptors CD86 and CD197 and alteration of antimicrobial peptides gene expression [ 94 ].…”