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"Candidatus Pelagibacter", with the single species "Ca. P. communis", was isolated in 2002 and given a specific name, although it has not yet been described as required by the bacteriological code. It is an abundant member of the SAR11 clade in the phylum Alphaproteobacteria. SAR11 members are highly dominant organisms found in both salt and fresh water worldwide and were originally known only from their rRNA genes, first identified in the Sargasso Sea in 1990 by Stephen Giovannoni's laboratory at Oregon State University and later found in oceans worldwide. "Ca. P. communis" and its relatives may be the most abundant organisms in the ocean, and quite possibly the most abundant bacteria in the entire world. It can make up about 25% of all microbial plankton cells, and in the summer they may account for approximately half the cells present in temperate ocean surface water. The total abundance of "Ca. P. communis" and relatives is estimated to be about 2 × 1028 microbes.
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The Rickettsiaceae are a family of bacteria. The genus Rickettsia is the most prominent genus within the family. The bacteria that eventually formed the mitochondrion is believed to have originated from this family. Most human pathogens in this family are in genus Rickettsia. They spend part of their lifecycle in the bodies of arthropods such as ticks or lice, and are then transmitted to humans or other mammals by the bite of the arthropod. It contains Gram-negative bacteria, very sensitive to environmental exposure, thus is adapted to obligate intracellular infection. Rickettsia rickettsii is considered the prototypical infectious organism in the group.
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Gammaproteobacteria is a class of bacteria in the phylum Pseudomonadota. It contains about 250 genera, which makes it the most genus-rich taxon of the Prokaryotes. Several medically, ecologically, and scientifically important groups of bacteria belong to this class. It is composed by all Gram-negative microbes and is the most phylogenetically and physiologically diverse class of Proteobacteria.
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Genomic streamlining is a theory in evolutionary biology and microbial ecology that suggests that there is a reproductive benefit to prokaryotes having a smaller genome size with less non-coding DNA and fewer non-essential genes. There is a lot of variation in prokaryotic genome size, with the smallest free-living cell's genome being roughly ten times smaller than the largest prokaryote. Two of the bacterial taxa with the smallest genomes are Prochlorococcus and Pelagibacter ubique, both highly abundant marine bacteria commonly found in oligotrophic regions. Similar reduced genomes have been found in uncultured marine bacteria, suggesting that genomic streamlining is a common feature of bacterioplankton. This theory is typically used with reference to free-living organisms in oligotrophic environments.
Ann Patricia Wood is a retired British biochemist and bacteriologist who specialized in the ecology, taxonomy and physiology of sulfur-oxidizing chemolithoautotrophic bacteria and how methylotrophic bacteria play a role in the degradation of odour causing compounds in the human mouth, vagina and skin. The bacterial genus Annwoodia was named to honor her contributions to microbial research in 2017.
References
- ↑ Thrash JC, Boyd A, Huggett MJ, Grote J, Carini P, Yoder RJ, Robbertse B, Spatafora JW, Rappe MS, Giovannoni SJ (2011). "Phylogenomic evidence for a common ancestor of mitochondria and the SAR11 clade". Sci Rep. 1: 13. Bibcode:2011NatSR...1E..13T. doi:10.1038/srep00013. PMC 3216501 . PMID 22355532.
- ↑ Euzéby JP, Parte AC. "Pelagibacteraceae". List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved June 2, 2021.
- ↑ Grote J, Thrash JC, Huggett MJ, Landry ZC, Carini P, Giovannoni SJ, Rappe MS (2012). "Streamlining and core genome conservation among highly divergent members of the SAR11 clade". mBio. 3 (5): 1–13. doi:10.1128/mBio.00252-12. PMC 3448164 . PMID 22991429.
Clark, M., Douglas, M., & Choi, J. (2018). Biology 2e. Houston, Texas: OpenStax. Retrieved from https://openstax.org/books/biology-2e/pages/1-introduction Ortmann, A. C., & Santos, T. T. (2016, July 6). Spatial and temporal patterns in the Pelagibacteraceae across an estuarine gradient. FEMS Microbiology Ecology, 92, 9. doi:https://doi.org/10.1093/femsec/fiw133
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