| Projects → Methanosphaera stadtmanae |
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Total production of methane on earth is about one billion tons per year. Most of it is produced in anoxic sediments and in ruminants, about 50% of the human population are mini-methane producers. Responsible for methane formation in humans are the methanogenic archaeal species Methanobrevibacter smithii and Methanosphaera stadtmanae. We sequenced the genome of M. stadtmanae in order to answer two questions: Why is M. stadtmanae - in contrast to other methanogens - restricted to methanol + H2 as substrate for methanogenesis, and are there specific adaptations of this organism to its instestinal environment? Here are the answers: The genome of M. stadtmanae lacks 37 protein-encoding sequences which are present in the sequenced genomes of all other methanogens. These include the genetic information for the synthesis of molybdopterin which is required for the enzyme catalyzing the first step of methanogenesis from CO2 + H2. Also, carbon monoxide dehydrogenase / acetyl-coenzyme A synthase genes are lacking, explaining why this organism needs acetate for growth. Sequences with up to 3.300 amino acids were detected which, with one exception, have not been found in the genomes of other methanogens or archaea, which have a repetitive structure, and which may represent surface-layer components which allow M. stadtmanae to successfully colonize in the intestine |
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