Methanosaeta thermophila
From MicrobeWiki, the student-edited microbiology resource
Methanosaeta thermophila
● ~Classification~
Organism Name: Methanosaeta thermophila PT Domain: Archaea Phylum: Euryarchaeota Class: Methanomicrobia Order: Methanosarcinales Family: Methanosaetaceae Genus: Methanosaeta
Species: Methanothrix thermophila Genus Species Strain: Methanosaeta thermophila PT Name History: Synonyms: Methanothrix thermophila PT Methanothrix thermophila DSM 6194 Equivalent names: Methanosaeta thermophila strain PT Methanosaeta thermophila str. PT
●~Description and Significance~
thermophila are nonmotile, nonsporulating, and thermophilic, which means they thrive at temperatures of 50ºC or higher. This microbe was discovered by a molecular technique using fluorogenic PCR (polymerase chain reaction, which amplifies DNA) to identify its methanotrophic characteristics and activity in marine anoxic microbial communities. This was accomplished by identifying and quantifying the mcrA genes. Following amplification, molecular analysis was performed by clone analysis of the 16S rRNA and mcrA genes. The mcrA genes (encoding the methyl coenzyme M reductase, specific to methanogenic archaea), are specific to the various phylogenetic groups of methanotropic Archaea. Methanosaeta thermophila was identified among the microbial communities in deep sediments and “methane seepages of Omine Ridge in the Nankai Trough accretionary prism,” (1). The addition of Methanosaeta to the methanoarchaeal genome sequence compilation offered an opportunity to gain significant insight into this intricate microbe and the unique use of comparative genomic approaches allows one to address the nature of these specific microbes and their biological influence and capability. Because these microbes are methanogens, they serve an important role as the producers of natural gas and have potential as creators of biofuels (fuels derived from a biomass).
●~Genome Structure~
The Methanosaeta thermophila’s genome has been entirely sequenced. These microbes possess circular chromosomes and do not contain plasmids. (The following genome sequence information, list, and map of the Methanosaeta thermophila chromosome was taken from eleventh source listed under the references section.) Genome Sequence: RS: NC_008553 Genome Sequence Length: 1879471 Statistics: Number of nucleotides: 1879471 Number of protein genes: 1696 Number of RNA genes: 51 Genome Statistics Number % of Total DNA, total number of bases total 100.00% DNA G+C number of bases 0.00% DNA scaffolds 0 100.00% Genes total number 0 100.00% Protein coding genes 0 0.00% RNA genes 0 0.00% rRNA genes 0 0.00% 5S rRNA 0 0.00% 16S rRNA 0 0.00% 18S rRNA 0 0.00% 23S rRNA 0 0.00% 28S rRNA 0 0.00% tRNA genes 0 0.00% Other RNA genes 0 0.00% Genes with function prediction 0 0.00% Genes without function prediction 0 0.00%
Genes w/o function with similarity 0 0.00%
Genes w/o function w/o similarity 0 0.00% Pseudo Genes 0 0.00% Genes assigned to enzymes 0 0.00% Genes connected to KEGG pathways 0 0.00% Genes not connected to KEGG pathway 0 0.00% Genes in ortholog clusters 0 0.00% Genes in paralog clusters 0 0.00% Genes in COGs 0 0.00% Genes in Pfam 0 0.00% Genes in TIGRfam 0 0.00% Genes in InterPro 0 0.00% Genes with IMG Terms 0 0.00% Genes in IMG Pathways 0 0.00% Obsolete Genes 0 0.00% Revised Genes 0 0.00% Pfam clusters 0 0.00% Paralogous groups 0 100.00% Orthologous groups 0 0.00%
●~Cell Structure and Metabolism~
Methanosaeta thermophila is circular (coccus), with one inner membrane and one cell wall. This microbe does not interact with other organisms, grows extremely slow, does not contain plasmids, does not possess flagella, but they do however produce gas vacuoles to help them move in aquatic environments. Gas vacuoles are cavities within the cytoplasm, which contain a gas similar to that of their surrounding atmosphere. These vacuoles serve as floatation devices because they decrease in size when subjected to increased hydrostatic pressure. So although they are nonmotile, their gas vacuoles allow some degree of flexibility in regards to how much movement they have in aquatic environments. Methanosaeta thermophila obtain their energy as a “thermophilic obligately-aceticlastic methane-producing archaeon,” which means that they produce methane from acetate, (4). Although approximately two-thirds of all methane is derived from the methyl group of acetate, Methanosaeta are able to utilize acetate as a substrate for methanogenesis. Methanosarcina is the only other genus of methanoarchaea that are capable of utilizing acetate as a substrate, as well as using H2/CO2, dimethylsulfide, and and methanethiol compounds as substrates. Unlike the faster-growing Methanosarcina, which prefers methylated compounds to acetate, Methanosaeta is a slow-growing specialist that utilizes acetate only.
●~Ecology~
The environment at which Methanosaeta thermophiles are found is aquatic (living and growing in water) and they exhibit optimal growth between 55-60°C. Although they are present in many environments, such as anaerobic digesters, anaerobic biofilms, sediments, and anaerobic sludges, they are predominantly found in rice paddies, which allow a continuous stream of water to flow through them. Acetate is the most important substrate for methanogenesis in rice paddies and studies have shown that the concentration of acetate in flooded rice paddies is in the 5-100 mM range, and Methanosaeta thermophiles are the predominant acetate-utilizing methanoarchaea in these aquatic rice paddies. Methanosaeta species are the most prevalent methanogenic archaea of the microbial population in numerous environments, including rough sludge digesters, solid wastes, sewage slush, and anaerobic reactors. During activation of anaerobic bioreactors, Methanosaeta species are widespread due to the high acetate concentration. However, as bioreactors become stable and attain their peak performance, the acetate concentration decreases, as well as the Methanosaeta population.