Evolution of oxygen on planet earth from cyanobacteria

Evolution of oxygen on planet earth from cyanobacteria

Description:

Cyanobacteria  also known as Cyanophyta, are a phylum consisting of free-living photosynthetic bacteria and the endosymbiotic plastids, a sister group to Gloeomargarita, that are present in some eukaryotes. They commonly obtain their energy through oxygenic photosynthesis.[4] The oxygen gas in the atmosphere of earth is produced by cyanobacteria of this phylum, either as free-living bacteria or as the endosymbiotic plastids. The name cyanobacteria comes from the color of the bacteria. Cyanobacteria, which are prokaryotes, are also called "blue-green algae"though some modern botanists restrict the term algae to eukaryotes. Cyanobacteria appear to have originated in freshwater or a terrestrial environment.

Morphology:

Each individual cell (each single cyanobacterium) typically has a thick, gelatinous cell wall. They lack flagella, but hormogonia of some species can move about by gliding along surfaces.] Many of the multicellular filamentous forms of Oscillatoria are capable of a waving motion; the filament oscillates back and forth. In water columns, some cyanobacteria float by forming gas vesicles, as in archaea These vesicles are not organelles as such. They are not bounded by lipid membranes but by a protein sheath. 

Ecology:

Cyanobacteria can be found in almost every terrestrial and aquatic habitat – oceans, fresh water, damp soil, temporarily moistened rocks in deserts, bare rock and soil, and even Antarctic rocks. 

Cyanobacterial growth is favored in ponds and lakes where waters are calm and have little turbulent mixing. Their life cycles are disrupted when the water naturally or artificially mixes from churning currents caused by the flowing water of streams or the churning water of fountains. For this reason blooms of cyanobacteria seldom occur in rivers unless the water is flowing slowly. Growth is also favored at higher temperatures which enable Microcystis species to outcompete diatoms and green-algae, and potentially allow development of toxins.

Based on environmental trends, models and observations suggest cyanobacteria will likely increase their dominance in aquatic environments. This can lead to serious consequences, particularly the contamination of sources of drinking water. Cyanobacteria can interfere with water treatment in various ways, primarily by plugging filters (often large beds of sand and similar media) and by producing cyanotoxins, which have the potential to cause serious illness if consumed. Consequences may also lie within fisheries and waste management practices. Anthropogenic eutrophication rising temperatures, vertical stratification and increased atmospheric carbon dioxide are contributors to cyanobacteria increasing dominance of aquatic ecosystems.

Cyanobacteria have been found to play an important role in terrestrial habitats. It has been widely reported that cyanobacteria soil crusts help to stabilize soil to prevent erosion and retain water. An example of a cyanobacterial species that does so is Microcoleus vaginatus. M. vaginatus stabilizes soil using a polysaccharide sheath that binds to sand particles and absorbs water.

Photosynthesis:

Carbon fixation:

Cyanobacteria use the energy of sunlight to drive photosynthesis  a process where the energy of light is used to synthesize organic compounds from carbon dioxide. Because they are aquatic organisms, they typically employ several strategies which are collectively known as a "carbon concentrating mechanism" to aid in the acquisition of inorganic carbon (CO

2 or bicarbonate Among the more specific strategies is the widespread prevalence of the bacterial microcompartments known as carboxysomes These icosahedral structures are composed of hexameric shell proteins that assemble into cage-like structures that can be several hundreds of nanometers in diameter. It is believed that these structures consists the CO

2-fixing enzyme, RuBisCO to the interior of the shell, as well as the enzyme carbonic anhydrase, using metabolic chanelling to enchance the local co2 concentration and thus to increase the efficacy of RUBISCO enzyme.

Nitrogen fixation:

Some cyanobacteria can fix atmospheric nitrogen in anaerobic conditions by means of specialized cells called heterocysts. Heterocyst-forming species are specialized for nitrogen fixation and are able to fix nitrogen into ammonia, nitrites, nitrates which can be absorbed the plants and get converted into proteins and nucleic acids atmospheric nitrogen is not bioavailable to plants except for those having endsymbiotic nitrogen fixing bacteria especially in plants belonging to fabaceace

Electronic transport:  

The photosynthetic machinery is embedded in the thylakoid membranes, with phycobilisomes acting as light-harvesting antennae attached to the membrane, giving the green pigmentation observed

 

 (with wavelengths from 450 nm to 660 nm) in most cyanobacteria.

While most of the high-energy electrons derived from water are used by the cyanobacterial cells for their own needs, a fraction of these electrons may be donated to the external environment via electrogenic activity

Metabolism:

In general, photosynthesis in cyanobacteria uses water as an electron donor and produces oxygen as a byproduct, though some may also use hydrogen sulfide a process which occurs among other photosynthetic bacteria such as the purple sulfur bacteria

Carbon dioxide is reduced to form carbohydrates via the Calvin cycle The large amounts of oxygen in the atmosphere are considered to have been first created by the activities of ancient cyanobacteria. They are often found as symbionts with a number of other groups of organisms such as fungi (lichens), corals, pteridophytes (Azolla), angiosperms (Gunnera), etc

Relationship with chloroplast:

Primary chloroplasts are cell organelles found in some eukaryotic lineages, where they are specialized in performing the photosynthesis. They are considered to have evolved from endosymbiotic cyanobacteria. After some years of debate, it is now generally accepted that the three major groups of primary endosymbiotic eukaryotes (i.e. green plants, red algae and glaucophytes form one large monophyletic group called Archaeplastida which evolved after one unique endosymbiotic event

Ability of DNA repair:

Cyanobacteria are challenged by environmental stresses and internally generated reactive oxygen species that cause  DNA damage Cyanobacteria possess numerous E.coli -like DNA repair genes Several DNA repair genes are highly conserved in cyanobacteria, even in small genomes, suggesting that core DNA repair processes such as recombinational repair  nucleotide excision repair and methyl-directed DNA mismatch repair are common among cyanobacteria

Natural genetic transformation:

Cyanobacteria are capable of natural genetic transformation  Natural genetic transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous DNA from its surroundings. For bacterial transformation to take place, the recipient bacteria must be in a state of competence, which may occur in nature as a response to conditions such as starvation, high cell density or exposure to DNA damaging agents. In chromosomal transformation, homologous transforming DNA can be integrated into the recipient genome by homologous recombination, and this process appears to be an adaptation for repairing DNA damage

Biotechnology and application:

Recent research has suggested the potential application of cyanobacteria to the generation of renewable energy by directly converting sunlight into electricity. Internal photosynthetic pathways can be coupled to chemical mediators that transfer electrons to external electrodes In the shorter term, efforts are underway to commercialize algae-based fuels such as diesel, gasoline, and jet fuel.

Researchers from a company called Algenol have cultured genetically modified cyanobacteria in sea water inside a clear plastic enclosure so they first make sugar (pyruvate) from CO

2 and the water via photosynthesis. Then, the bacteria secrete ethanol from the cell into the salt water. As the day progresses, and the solar radiation intensifies, ethanol concentrations build up and the ethanol itself evaporates onto the roof of the enclosure. As the sun recedes, evaporated ethanol and water condense into droplets, which run along the plastic walls and into ethanol collectors, from where it is extracted from the enclosure with the water and ethanol separated outside the enclosure. As of March 2013, Algenol was claiming to have tested its technology in Florida and to have achieved yields of 9,000 US gallons per acre per year.[105] This could potentially meet US demands for ethanol in gasoline in 2025, assuming a B30 blend, from an area of around half the size of California's San Bernardino County, requiring less than one-tenth of the area than ethanol from other biomass.

Cyanobacteria may possess the ability to produce substances that could one day serve as anti-inflammatory agents and combat bacterial infections in humans

Spirulina's extracted blue color is used as a natural food coloring in gum and candy.

Health risk:

Some cyanobacteria can produce neurotoxins, cytotoxins, endotoxins, and hepatotoxins (e.g., the microcystin-producing bacteria genus microcystis which are collectively known as cyanotoxins.

Recent studies suggest that significant exposure to high levels of cyanobacteria producing toxins such as BMAA (β-Methylamino-l-alanine) is a non-proteinogenic amino acid produced by cyanobacteria. BMAA is a neurotoxin and its potential role in various neurodegenerative disorders is the subject of scientific research. BMAA can cause amyotrophic lateral sclerosis (ALS). People living within half a mile of cyanobacterially contaminated lakes have had a 2.3 times greater risk of developing ALS than the rest of the population.

Dietary supplementary:

Despite the associated toxins which many members of this phylum produce, some microalgae also contain substances of high biological value, such as polyunsaturated fatty acids, amino acids, proteins, pigments, antioxidants, vitamins, and minerals.

Sulfate polysaccharides exhibit immunomodulatory, antitumor, antithrombotic, anticoagulant, anti-mutagenic, anti-inflammatory, antimicrobial, and even antiviral activity against HIV, herpes, and hepatitis.

Research facts:

• The great oxidation event happen when the Earth’s atmosphere and Ocean experience a rise in oxygen

• This event led to the mass extinction of many existing species

• It was triggered by oxygen producing cyanobacteria

• Which enabled the subsequent development of multi cellular life form

• For the first half of the Earth’s history there was no oxygen in atmosphere

• Oxygen started to appear about 2.4 billion years ago

• Most of the bacteria thriving on earth were anaerobic

• Anaerobic bacteria metabolized their food without oxygen

• Researchers are not sure when exactly life began

• But the oldest known fossils of these micro-organism date back 3.5 billion years

• Scientist believe that simple life-form called cyanobacteria are responsible for great oxidation event.

• Cyanobacteria are micro-scopic organism that sometimes form bright-blue green layers in oceans

• Back then cyanobacteria found a way to take energy from sunlight (photosynthesis) and use to make sugars(pyruvate) out of water and carbon dioxide 

• In bacteria, photosynthesis produces oxygen as waste product that is pumped into the air.

• The great oxidation event occurred  when cyanobacteria released unwanted oxygen into air, leading to major transformation into atmosphere.

• Cyanobacteria flourished and the minerals and other sinks became saturated, they could no longer absorb  the oxygen been produced it build up in the water and in the air

• But oxygen was toxic to the anaerobic bacteria living in the ocean

• This led to the mass extinction og countless species of bacteria

• As the oxygen quantity increased some of it combined with methane to create carbon dioxide

• This led to a drop in levels of methane and the earth temperature dropped.

• This triggered a massive Glaciations event.

• Cyanobacteria was also threatened and their numbers dropped along with nearly all other LIFE ON EARTH many cyanobacteria were able to produce specialized cells 

• Scientist believe that this multicellularity could have given many advantages to cyanobacteria and help them survive in the new environment

• This improvement would eventually lead to the development of new life forms

reference:

 "Cyanophyceae". Access Science. doi:10.1036/1097-8542.175300. Retrieved 21 April 2011.

 Oren A (September 2004). "A proposal for further integration of the cyanobacteria under the Bacteriological Code". International Journal of Systematic and Evolutionary Microbiology. 54 (Pt 5): 1895–902. doi:10.1099/ijs.0.03008-0. PMID 15388760.

 Komárek J, Kaštovský J, Mareš J, Johansen JR (2014). "Taxonomic classification of cyanoprokaryotes (cyanobacterial genera) 2014, using a polyphasic approach" (PDF). Preslia. 86: 295–335.

 "Life History and Ecology of Cyanobacteria". University of California Museum of Paleontology. Retrieved 17 July 2012.

 Hamilton TL, Bryant DA, Macalady JL (February 2016). "The role of biology in planetary evolution: cyanobacterial primary production in low-oxygen Proterozoic oceans". Environmental Microbiology. 18 (2): 325–40. doi:10.1111/1462-2920.13118. PMC 5019231. PMID 26549614.

 "cyan | Origin and meaning of cyan by Online Etymology Dictionary". www.etymonline.com. Retrieved 21 January 2018.

 "Henry George Liddell, Robert Scott, A Greek-English Lexicon, κύα^νος". www.perseus.tufts.edu. Retrieved 21 January 2018.

 "Taxonomy Browser – Cyanobacteria". National Center for Biotechnology Information. NCBI:txid1117. Retrieved 12 April 2018.

 Allaby, M, ed. (1992). "Algae". The Concise Dictionary of Botany. Oxford: Oxford University Press.

 Stal LJ, Cretoiu MS (2016). The Marine Microbiome: An Untapped Source of Biodiversity and Biotechnological Potential. Springer.

 Liberton M, Pakrasi HB (2008). "Chapter 10. Membrane Systems in Cyanobacteria". In Herrero A, Flore E (eds.). The Cyanobacteria: Molecular Biology, Genomics, and Evolution. Norwich, United Kingdom: Horizon Scientific Press. pp. 217–87. ISBN 978-1-904455-15-8.

 Liberton M, Page LE, O'Dell WB, O'Neill H, Mamontov E, Urban VS, Pakrasi HB (February 2013). "Organization and flexibility of cyanobacterial thylakoid membranes examined by neutron scattering". The Journal of Biological Chemistry. 288 (5): 3632–40. doi:10.1074/jbc.M112.416933. PMC 3561581. PMID 23255600.

 Whitton BA, ed. (2012). "The fossil record of cyanobacteria". Ecology of Cyanobacteria II: Their Diversity in Space and Time. Springer Science & Business Media. pp. 17–. ISBN 978-94-007-3855-3.

 Basic Biology (18 March 2016). "Bacteria".

 Dodds WK, Gudder DA, Mollenhauer D (1995). "The ecology of 'Nostoc'". Journal of Phycology. 31: 2–18

-Liyaqath ali