Evolution of bacteria

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Colorized scanning electron micrograph showing carbapenem-resistant Klebsiella pneumoniae interacting with a human neutrophil. Klebsiella pneumoniae Bacterium (13383411493).jpg
Colorized scanning electron micrograph showing carbapenem-resistant Klebsiella pneumoniae interacting with a human neutrophil.

The evolution of bacteria has progressed over billions of years since the Precambrian time with their first major divergence from the archaeal/eukaryotic lineage roughly 3.2-3.5 billion years ago. [1] [2] This was discovered through gene sequencing of bacterial nucleoids to reconstruct their phylogeny. Furthermore, evidence of permineralized microfossils of early prokaryotes was also discovered in the Australian Apex Chert rocks, dating back roughly 3.5 billion years ago [3] during the time period known as the Precambrian time. This suggests that an organism in of the phylum Thermotogota (formerly Thermotogae) [4] was the most recent common ancestor of modern bacteria.

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Further chemical and isotopic analysis of ancient rock reveals that by the Siderian period, roughly 2.45 billion years ago, [5] oxygen had appeared. This indicates that oceanic, photosynthetic cyanobacteria evolved during this period because they were the first microbes to produce oxygen as a byproduct of their metabolic process. [6] Therefore, this phylum was thought to have been predominant roughly 2.3 billion years ago. However, some scientists argue they could have lived as early as 2.7 billion years ago, [7] as this was roughly before the time of the Great Oxygenation Event, meaning oxygen levels had time to increase in the atmosphere before it altered the ecosystem during this event.

The rise in atmospheric oxygen led to the evolution of Pseudomonadota (formerly proteobacteria). Today this phylum includes many nitrogen fixing bacteria, pathogens, and free-living microorganisms. This phylum evolved approximately 1.5 billion years ago during the Paleoproterozoic era. [8]

However, there are still many conflicting theories surrounding the origins of bacteria. Even though microfossils of ancient bacteria have been discovered, some scientists argue that the lack of identifiable morphology in these fossils means they can not be utilised to draw conclusions on an accurate evolutionary timeline of bacteria. Nevertheless, more recent technological developments means more evidence has been discovered.

Defining bacteria

Bacteria are prokaryotic microorganisms that can either have a bacilli, spirilli, or cocci shape and measure between 0.5-20 micrometers. They were one of the first living cells to evolve [9] and have spread to inhabit a variety of different habitats including hydrothermal vents, glacial rocks, and other organisms. They share characteristics with eukaryotic cells including the cytoplasm, cell membrane, and ribosomes. Some unique bacterial features include the cell wall (also found in plants and fungi), flagella (not common for all bacteria), and the nucleoid.[ citation needed ]

Bacteria can metabolise in different ways, most commonly by heterotrophic or autotrophic (either photosynthetic or chemosynthetic) processes. Bacteria reproduce through binary fission, though they can still share genetic information between individuals either by transduction, transformation, or conjugation.[ citation needed ]

Process of bacterial evolution

Bacteria evolve in a similar process to other organisms. This is through the process of natural selection, whereby beneficial adaptations are passed onto future generations until the trait becomes common within the entire population. [10] However, since bacteria reproduce via binary fission—a form of asexual reproduction—the daughter cell and parent cell are genetically identical. This makes bacteria susceptible to environmental pressures, an issue that is overcome by sharing genetic information via transduction, transformation, or conjugation. This allows for new genetic and physical adaptations to develop, allowing bacteria to adapt to their environment and evolve. Furthermore, bacteria can reproduce in as little as 20 minutes, [11] which allows for fast adaptation, meaning new strains of bacteria can evolve quickly. This has become an issue regarding antibiotic resistant bacteria.[ citation needed ]

Thermophile bacteria from deep-sea vent. This organism eats sulfur and hydrogen and fixes its own carbon from carbon dioxide. Thermophile bacteria2.jpg
Thermophile bacteria from deep-sea vent. This organism eats sulfur and hydrogen and fixes its own carbon from carbon dioxide.

Thermotogales

Thermotogota bacteria are typically thermophilic or hyperthermophilic, gram-negative staining, anaerobic organisms that can live near hydrothermal vents where temperatures can range between 55-95 °C. They are thought to be some of the earliest forms of life. Evidence of bacteria has been discovered in the Australian Apex Chert near ancient hydrothermal vents. [12] [13] These rocks date back 3.46 billion years and, because oxygen was not present in large quantities in Earth's early atmosphere, these fossils are thought to represent early thermophilic bacteria, which do not require oxygen to survive. [14] Furthermore, living species such as Thermotoga neapolitana , which are thought to resemble their ancestral form, live around these vents, which some scientists have used as evidence to support this theory.[ citation needed ]

More recent evidence suggests that Thermotogales evolved roughly between 3.2-3.5 billion years ago. This evidence was collected via gene sequencing of bacterial nucleoids to reconstruct their phylogeny. [1] [2] The first major divergence within the Thermotogales phylum was between Thermotogaceae and Fervidobacteriaceae, however, it is yet to be determined as to when this occurred. The family of Thermotogaceae then diverged into the genus Thermotoga and the genus Pseudothermotoga . [15] The genus Thermotoga represents the majority of existing hyperthermophiles and are unique in that they are wrapped in an outer membrane that is referred to as a "toga". Some extant Thermotoga species include T. neapolitana.[ citation needed ]

Thermotogale phylogeny

Colourful Thermophilic (Heat-loving) Archaebacteria Stain. Archaebacteria are nowadays regarded as their own domain Archaea, distinct from Thermotogales. Colourful Thermophilic Archaebacteria Stain in Midway Geyser Basin.jpg
Colourful Thermophilic (Heat-loving) Archaebacteria Stain. Archaebacteria are nowadays regarded as their own domain Archaea, distinct from Thermotogales.

The phylogeny based on the work of the All-Species Living Tree Project. [15]

Thermotogales

Cyanobacteria

Cyanobacteria or blue green-algae is a gram negative bacteria, a phylum of photosynthetic bacteria that evolved between 2.3-2.7 billion years ago. [16] This prokaryote produces oxygen as a byproduct of its photosynthetic processes. [17] They have made a distinctive impact in pharmaceutical and agricultural industry due to their potential of making bioactive compounds with antibacterial, anti-fungal, antiviral, and anti-algal properties. Typically they form motile filaments referred to as hormogonia, which can form colonies and then bud and travel to colonise new areas. They have been located in environments including freshwater, oceans, soil and rock (both damp and dry), as well as arctic rock.[ citation needed ]

These organisms had evolved photosynthetic reaction centres and became the first oxygen producing autotrophs to appear in the fossil record. They utilise sunlight in order to drive their metabolic processes, which removes carbon dioxide from the atmosphere and releases oxygen. [18] Due to this trait some scientist credit this phylum to causing the Great Oxygenation Event roughly 2.3 billion years ago [19]

English: Bloom of cyanobacteria in a freshwater pond. This accumulation in one corner of the pond was caused by wind drift. It looked as if someone had dumped a bucket color into the water. Cyanobacteria Aggregation2.jpg
English: Bloom of cyanobacteria in a freshwater pond. This accumulation in one corner of the pond was caused by wind drift. It looked as if someone had dumped a bucket color into the water.

However, the closest known relatives of oxygen producing Cyanobacteria did not produce oxygen. [20] These relatives are Melainabacteria and Sericytochromatia, neither of which can photosynthesise. Through genetic sequencing, scientists discovered that these two groups did not have any remnants of the genes required for the functioning of photosynthetic reactions. [20] This suggests that Cyanobacteria, Melainabacteria, and Sericytochromatia evolved from a non-photosynthetic common ancestor.[ citation needed ]

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The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope. Cells emerged on Earth about 4 billion years ago. All cells are capable of replication, protein synthesis, and motility.

<span class="mw-page-title-main">Photosynthesis</span> Biological process to convert light into chemical energy

Photosynthesis is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabolism. Photosynthesis usually refers to oxygenic photosynthesis, a process that produces oxygen. Photosynthetic organisms store the chemical energy so produced within intracellular organic compounds like sugars, glycogen, cellulose and starches. To use this stored chemical energy, an organism's cells metabolize the organic compounds through cellular respiration. Photosynthesis plays a critical role in producing and maintaining the oxygen content of the Earth's atmosphere, and it supplies most of the biological energy necessary for complex life on Earth.

<span class="mw-page-title-main">Symbiogenesis</span> Evolutionary theory holding that eukaryotic organelles evolved through symbiosis with prokaryotes

Symbiogenesis is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and possibly other organelles of eukaryotic cells are descended from formerly free-living prokaryotes taken one inside the other in endosymbiosis. Mitochondria appear to be phylogenetically related to Rickettsiales bacteria, while chloroplasts are thought to be related to cyanobacteria.

<span class="mw-page-title-main">Cyanobacteria</span> Phylum of photosynthesising prokaryotes

Cyanobacteria, also called Cyanobacteriota or Cyanophyta, are a phylum of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" refers to their bluish green (cyan) color, which forms the basis of cyanobacteria's informal common name, blue-green algae, although as prokaryotes they are not scientifically classified as algae.

<span class="mw-page-title-main">Plastid</span> Plant cell organelles that perform photosynthesis and store starch

A plastid is a membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms. Plastids are considered to be intracellular endosymbiotic cyanobacteria.

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<i>Chloroflexus aurantiacus</i> Species of bacterium

Chloroflexus aurantiacus is a photosynthetic bacterium isolated from hot springs, belonging to the green non-sulfur bacteria. This organism is thermophilic and can grow at temperatures from 35 to 70 °C. Chloroflexus aurantiacus can survive in the dark if oxygen is available. When grown in the dark, Chloroflexus aurantiacus has a dark orange color. When grown in sunlight it is dark green. The individual bacteria tend to form filamentous colonies enclosed in sheaths, which are known as trichomes.

<i>Prochlorococcus</i> Genus of bacteria

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References

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  2. 1 2 Brown, J R Doolittle, W F (December 1997). "Archaea and the prokaryote-to-eukaryote transition". Microbiology and Molecular Biology Reviews. 61 (4): 456–502. doi:10.1128/mmbr.61.4.456-502.1997. PMC   232621 . PMID   9409149.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ↑ "31. Ancient Life: Apex Chert Microfossils". www.lpi.usra.edu. Retrieved 2019-05-21.
  4. ↑ Di Giulio, Massimo (December 2003). "The Universal Ancestor and the Ancestor of Bacteria Were Hyperthermophiles". Journal of Molecular Evolution. 57 (6): 721–730. Bibcode:2003JMolE..57..721D. doi:10.1007/s00239-003-2522-6. PMID   14745541. S2CID   7041325.
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  7. ↑ "When Did Bacteria Appear?". Astrobiology Magazine. 2004-04-18. Archived from the original on 2019-01-12. Retrieved 2019-05-21.
  8. ↑ Degli Esposti, Mauro (2014-11-27). "Bioenergetic Evolution in Proteobacteria and Mitochondria". Genome Biology and Evolution. 6 (12): 3238–3251. doi: 10.1093/gbe/evu257 . PMC   4986455 . PMID   25432941.
  9. ↑ Hartman, H; Matsuno, K (1993). The Origin and Evolution of the Cell. World Scientific. pp. 1–446. doi:10.1142/9789814536219. ISBN   9789810212629.
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  11. ↑ "About Microbiology – Bacteria". microbiologyonline.org. Archived from the original on 2019-11-27. Retrieved 2019-05-21.
  12. ↑ Brasier, M. D. (2011). Geology and putative microfossil assemblage of the c. 3460 Ma 'Apex Chert', Chinaman Creek, Western Australia : a field and petrographic guide. Geological Survey of Western Australia. ISBN   9781741683660. OCLC   748237320.
  13. ↑ "Apex Chert Microfossils". ResearchGate. Retrieved 2019-05-21.
  14. ↑ Frock, Andrew D.; Notey, Jaspreet S.; Kelly, Robert M. (2010). "The genus Thermotoga: Recent developments". Environmental Technology. 31 (10): 1169–1181. doi:10.1080/09593330.2010.484076. PMC   3752655 . PMID   20718299.
  15. 1 2 Silva Comprehensive Ribosomal RNA Database (September 2015). "16S rRNA-based LTP release 123 (full tree)" (PDF). Archived from the original (PDF) on 2019-06-07. Retrieved 2019-06-07.
  16. ↑ Berman-Frank, Ilana; Lundgren, Pernilla; Falkowski, Paul (2003). "Nitrogen fixation and photosynthetic oxygen evolution in cyanobacteria". Research in Microbiology. 154 (3): 157–164. doi: 10.1016/s0923-2508(03)00029-9 . PMID   12706503.
  17. ↑ Hamilton, Trinity L.; Bryant, Donald A.; Macalady, Jennifer L. (2015-12-21). "The role of biology in planetary evolution: cyanobacterial primary production in low-oxygen Proterozoic oceans". Environmental Microbiology. 18 (2): 325–340. doi:10.1111/1462-2920.13118. PMC   5019231 . PMID   26549614.
  18. ↑ Tandeau de Marsac, Nicole; Houmard, Jean (January 1993). "Adaptation of cyanobacteria to environmental stimuli: new steps towards molecular mechanisms". FEMS Microbiology Letters. 104 (1–2): 119–189. doi: 10.1111/j.1574-6968.1993.tb05866.x .
  19. ↑ "Great Oxidation Event: More oxygen through multicellularity". ScienceDaily. Retrieved 2019-06-07.
  20. 1 2 "The bacteria that changed the world". evolution.berkeley.edu. May 2017. Retrieved 2019-06-07.

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