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/eukcaryotic 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 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 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

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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), flagella (not common for all bacteria), and the nucleoid.

They metabolise is a different ways, but this most common is either by a heterotrophic or autotrophic (either photosynthetic or chemosynthetic) process. They also reproduce through binary fission. They can still share genetic information between individuals either by transduction, transformation, or conjugation.

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, bacteria reproduce via binary fission, which is a form of asexual reproduction meaning the daughter cell and the parent cell are genetically identical. This makes bacteria susceptible to environmental pressures. This is overcome by sharing genetic information by either transduction, transformation, or conjugation. This allows for new genetic and physical adaptations to evolve, thus 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.

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

These organisms 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 these organisms have been discovered in the Australian Apex Chert near ancient hydrothermal vents. [12] [13] These rocks date back 3.46 billion years and these fossils are thought to have belonged to early thermophilic bacteria. This is because these organisms do not require oxygen to survive, which was an element that was not present in large quantities in Earth's early atmosphere. [14] Furthermore, this phylum still has living species such as Thermotoga neapolitana, which still largely resemble their ancestral form and still live around these vents, which some scientists have used as evidence to support this theory.

More recent evidence has emerged, which 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 represent the majority of existing hyperthermophiles and are unique in that they are wrapped in an outer membrane that is referred to as a "toga". Today some existing species part of the Thermotoga genus include T. neapolitana.

Thermotogale Phylogeny

English: Colourful Thermophilic Archaebacteria (Heat-loving bacteria) Stain Colourful Thermophilic Archaebacteria Stain in Midway Geyser Basin.jpg
English: Colourful Thermophilic Archaebacteria (Heat-loving bacteria) Stain

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

Thermotogales
Thermotogaceae
Thermotoga
 

T. naphthophila

 
 
 

T. petrophila

 
 
 

T. maritima (type sp.)

 
 

T. neapolitana

 
 
 
 
Pseudothermotoga
 
 

P. hypogea

 
 

P. thermarum

 
 
 
 

P. subterranea

 
 
 

P. elfii

 
 

P. lettingae

 
 
 
 
 
Fervidobacteriaceae
Fervidobacterium
 
 

F. changbaicum

 
 

F. islandicum

 
 
 
 

F. nodosum (type sp.)

 
 
 

F. gondwanense

 
 

F. riparium

 
 
 
 
Thermosipho
 

T. activus

 
 
 

T. geolei

 
 
 

T. atlanticus

 
 
 
 

T. affectus

 
 

T. melanesiensis

 
 
 
 

T. globiformans

 
 
 

T. africanus (type sp.)

 
 

T. japonicus

 
 
 
 
 
 
 
 
 

Cyanobacteria Bacteria

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.

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.

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Gram-positive bacteria Bacteria that give a positive result in the Gram stain test

Gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their cell wall.

Symbiogenesis An evolutionary theory holding that eukaryotic organelles evolved through symbiosis with prokaryotes

Symbiogenesis, or endosymbiotic theory, is an evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms, first articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by Lynn Margulis in 1967. It holds that the organelles distinguishing eukaryote cells evolved through symbiosis of individual single-celled prokaryotes . 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 proteobacteria, and chloroplasts to nitrogen-fixing filamentous cyanobacteria. Among the many lines of evidence supporting symbiogenesis are that new mitochondria and plastids are formed only through binary fission, and that cells cannot create new ones otherwise; that the transport proteins called porins are found in the outer membranes of mitochondria, chloroplasts and bacterial cell membranes; that cardiolipin is found only in the inner mitochondrial membrane and bacterial cell membranes; and that some mitochondria and plastids contain single circular DNA molecules similar to the chromosomes of bacteria.

Cyanobacteria Phylum of photosynthesising prokaryotes

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Plastid membrane-bound DNA-containing organelle found in the cytoplasm of autotrophic eukaryotes (plants, some protists) that functions as the site of manufacture and storage of important chemical compounds

The plastid is a membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms. They are considered endosymbiotic Cyanobacteria, related to the Gloeomargarita. Plastids were discovered and named by Ernst Haeckel, but A. F. W. Schimper was the first to provide a clear definition. Plastids are the site of manufacture and storage of important chemical compounds used by the cells of autotrophic eukaryotes. They often contain pigments used in photosynthesis, and the types of pigments in a plastid determine the cell's color. They have a common evolutionary origin and possess a double-stranded DNA molecule that is circular, like that of prokaryotic cells.

Unicellular organism Organism that consists of only one cell

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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. pp. 456–502. OCLC   679124743.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. ISSN   0022-2844. PMID   14745541.
  5. ↑ Zimmer, Carl (2013-10-03). "The Mystery of Earth's Oxygen". The New York Times. ISSN   0362-4331 . Retrieved 2019-05-21.
  6. ↑ "The Rise of Oxygen". Astrobiology Magazine. 2003-07-30. Retrieved 2019-05-21.
  7. ↑ "When Did Bacteria Appear?". Astrobiology Magazine. 2004-04-18. 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. ISSN   1759-6653. PMID   25432941.
  9. ↑ Hartman, H; Matsuno, K (1993). "The Origin and Evolution of the Cell". The Origin and Evolution of the Cell. WORLD SCIENTIFIC: 1–446. doi:10.1142/9789814536219. ISBN   9789810212629.
  10. ↑ "Evolution Resources from the National Academies". www.nas.edu. Retrieved 2019-05-21.
  11. ↑ "About Microbiology – Bacteria". microbiologyonline.org. 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. ISSN   0959-3330. PMC   3752655 . PMID   20718299.
  15. 1 2 Silva Comprehensive Ribosomal RNA Database (September 2015). "16S rRNA-based LTP release 123 (full tree)" (PDF).
  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. ISSN   0923-2508. 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. ISSN   1462-2912. 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. ISSN   0378-1097.
  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. Retrieved 2019-06-07.
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