Despite the name, cyanobacteria are not really algae. Instead, they are multicellular organisms that obtain their energy from photosynthesis. They are also known as Cyanophyta.
Among the most primitive multicellular systems in Nature, filamentous heterocyst-forming cyanobacteria are characterized by the presence of vegetative cells that fix carbon dioxide (CO2) through oxygenic photosynthesis and heterocysts that fix nitrogen (N2) through synthesis and degradation of Cyanophycin. They are found in terrestrial and polar environments and have thick cell walls. They produce large amounts of cytotoxins and neurotoxins and are considered potential hazards to humans. Despite their potential hazards, cyanobacteria are therapeutically useful.
During the early stages of heterocyst development, the vegetative cells are arrested and the heterocysts are actively developing. This coexistence relies on the simultaneous operation of opposite transcriptional programs. The two cell types share a common outer membrane, but their cell walls do not enter a septum. There are proteinaceous structures called septal junctions, which join cells to the filament. They are important for the behavior and multicellularity of heterocyst-forming cyanobacteria. These structures resemble gap junctions found in metazoans and represent convergent evolution.
Septal junctions are important for heterocyst-forming cyanobacteria because they serve as a pathway for intercellular molecular transfer. This is essential for the nutrition of heterocysts and vegetative cells, and also for signaling. There are two proteinaceous structures associated with septal junctions, and they are named based on the original descriptions. The two proteins are called FraC and FraD, and they are encoded in an operon.
The FraC and FraD genes were found to be clustered together, and these proteins are thought to work together. However, these proteins are incorporated into the cell membrane independently of each other. They are also known to participate in the formation of a cell-cell joining complex, but these proteins may not be required for this process. They are also known to have a role in the turnover of peptidoglycan in unicellular bacteria, and they may also function as cell wall amidases.
In filamentous heterocyst-forming bacteria, septal junctions are involved in the formation of nanopores. Nanopores are holes in the peptidoglycan mesh, and they are believed to accommodate septal junctions. They range in size from 7-8 nm, and the number of nanopores varies depending on the growth condition.
Responsibilities for oxygenation of Earth’s atmosphere
During the early Earth, cyanobacteria were among the first organisms to produce oxygen. These organisms used photosynthesis to generate oxygen. Photosynthesis is a biological process that converts sunlight into microbial energy, which is then used to perform various metabolic tasks. The process is known as anoxygenic photosynthesis. These bacteria were also able to oxidize water and sulfide to form elemental sulfur.
Cyanobacteria were also known to use hydrogen to fix carbon dioxide, an important process that helps to keep our planet’s atmosphere in balance. These bacteria also produced ozone, which is a sunscreen that helps protect the Earth’s surface from harmful UV radiation. Ozone is one of the most important components of Earth’s atmosphere. It shields the Earth from harmful UV radiation and is also a greenhouse gas.
It is known that oceanic cyanobacteria were among the earliest known organisms to produce oxygen. These organisms were also among the first to form multicellular forms. These multicellular forms could produce more oxygen than their single-celled cousins. This was one of the most important developments in the evolution of life on Earth. The cyanobacteria were also key players in the Great Oxidation Event, a period in Earth’s history during which atmospheric oxygen levels dramatically increased. These oxygen-producing bacteria are now found throughout Earth’s oceans, rivers, lakes, and soils.
The ancient world is dotted with fossils of these organisms. These fossils have been interpreted as evidence of the existence of oxygen-producing cyanobacteria. However, these fossils are also believed to have been produced by primitive bacteria. These fossils are preserved in ancient rocks, such as stromatolites. The fossils have been identified as far back as 3.7 billion years ago when oxygen-producing cyanobacteria first appeared on Earth.
Cyanobacteria are also known to produce cyanotoxins, which can be toxic to humans. In addition, cyanobacteria are important model organisms. They have been used to study many different biochemical processes, and are also used as a food source and for dietary supplements. They also have applications in biotechnology, such as in the production of bioethanol and food coloring.
Cyanobacteria also play an important role in the evolution of oxygen-dependent organisms. They can perform anoxygenic and oxygenic photosynthesis simultaneously. They also can use water as a source of energy for photosynthesis. This allows them to live in a wide variety of environments.
Characteristics of cyanobacterial clades
Phylogenetic studies of cyanobacteria have revealed several key features. Some of these features include the presence of a wall-like layer in chloroplasts, a peptidoglycan meshwork structure, and a sulfolipid. They also showed that chloroplasts are encoded by a single clade, a clade that is also found in land plants. This clade is separated from other Cyanobacteria.
The phylogenetic tree was constructed using concatenated sequences of 32 conserved proteins. The cyanobacterial clades are divided into eight groups, eight of which were strongly supported. The clades are divided into five morphotypes. A clade containing Prochlorococcus Marinus, Prochlorococcus cerebriform, Oxygen tenuis, Phormidium corium, and Phormidium aerugineo-caeruleum was found to be the most significant group. This clade is found in oligotrophic to mesotrophic conditions.
Cyanobacterial clades are characterized by their supreme minimalization. The solitary cells are shaped like a trichome and divide in a single plane perpendicular to the longitudinal axis. The apical cells are either slightly conical or rounded. The cells have radial thylakoids in the centroplasma. The cells are about six to seven um wide. They also have blue-green filaments and sheaths that are 0.5 um thick. The apical cells have apical carboxysomes. These proteins are distinct from the a-type carboxysomes found in Synechococcus.
Another key feature is the presence of two galactolipids, one of which is Sulfoquinovosyl diacylglycerol. These lipids are also present in land plants. The presence of this lipid is also found in heterocyst-forming cyanobacteria. It is also the result of EGT in the chloroplast genome.
A clade of heterocyst-forming cyanobacteria, known as akinete-forming cyanobacteria, was also found to form a distinct clade. It was further characterized by the presence of three conserved signature proteins. This is the first time a molecular signature has been detected in a heterocyst-forming cyanobacterium. It also indicates the monophyly of the clade.
A third feature is the presence of synteny, which is evidence of a missing RNA polymerase subunit. Another feature is the presence of chloroplast-encoded proteins, which are colored. This is a result of the cyanobacteria’s origin. The chloroplasts contain tri- and Tetragalactosyl diacylglycerols.
Cyanobacteria are found in freshwater, oceans, and terrestrial environments. They are members of the oxygen-evolving prokaryotic lineage. They also belong to the picoplankton community. They are adapted to diverse environments, including freshwater, seawater, lakes, rivers, ponds, and soils.
Health effects of exposure to cyanobacteria
Across the globe, harmful cyanobacteria are known to have adverse impacts on human health. This includes a variety of adverse health outcomes, including chronic illness and death, as well as deaths in livestock, birds, and fish. These illnesses are known to be caused by toxic cyanotoxins, which are released by the cyanobacteria during harmful algal blooms.
The adverse health effects of exposure to cyanobacteria vary among individuals depending on their individual physiology and how they are exposed to the toxins. Affected individuals may experience gastrointestinal symptoms, skin rashes, allergies, hay fever-like symptoms, respiratory distress, and kidney damage. Symptoms are often attributed to the individual’s immune system, but it is not known if the individual’s immune system is the primary cause of the illness.
Human exposure to cyanobacteria may occur through ingestion, aspiration, direct skin contact, and inhalation. These routes are likely the most relevant routes for exposure to cyanobacterial metabolites.
Symptoms of illness in animals exposed to cyanobacteria are similar to those in humans. Exposure to cyanotoxins may result in vomiting, diarrhea, skin rashes, ataxia, muscle pain, headache, and fatigue. Symptoms may also be associated with kidney damage, liver injury, and severe respiratory illness.
The most common sentinel animal is a dog, but ruminants and other animals may be at risk for exposure to harmful cyanobacteria. These animals may be exposed to surface water bodies during recreational activities.
The risk of cyanobacteria-associated illness is highest among sensitive subpopulations, which have an underdeveloped mucosal immune system. In addition to the gastrointestinal effects of exposure, cyanotoxins have also been associated with skin rashes and allergic reactions.
A significant data gap exists regarding oral exposure to cyanobacterial bloom components. This can be addressed through extensive monitoring and outreach activities. Regulatory officials should develop monitoring programs, educational materials, and outreach activities. If you think you have been exposed to cyanobacteria, you should seek medical treatment.
Acute illnesses caused by cyanotoxins include skin rashes, hay fever like symptoms, respiratory failure, and kidney damage. These illnesses may be caused by the presence of cyanotoxins in the drinking water, but they have also been reported among individuals who were exposed to contaminated water during recreational water activities.
Health A to Z. (n.d.). HSE.ie. https://www2.hse.ie/az/
U.S. National Library of Medicine. (n.d.). https://www.ncbi.nlm.nih.gov/
Directory Health Topics. (n.d.). https://www.healthline.com/directory/topics
Health A-Z. (2022, April 26). Verywell Health. https://www.verywellhealth.com/health-a-z-4014770
Harvard Health. (2015, November 17). Health A to Z. https://www.health.harvard.edu/health-a-to-z
Health Conditions A-Z Sitemap. (n.d.). EverydayHealth.com. https://www.everydayhealth.com/conditions/