Cyanobacteria, also known as Cyanophyta, are a phylum of Gram-negative bacteria that obtain energy via photosynthesis. The name cyanobacteria comes from their color, giving them their other name, "blue-green algae", though modern botanists restrict the term algae to eukaryotes and do not apply it to cyanobacteria, which are prokaryotes. They appear to have originated in freshwater or a terrestrial environment. Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria.
The plastid is a membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosymbiotic Cyanobacteria. Examples include chloroplasts, chromoplasts, and leucoplasts.
A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but lichens are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); a powder-like appearance (leprose); or other growth forms.
Nostoc, also known as star jelly, troll’s butter, witch's butter, and witch’s jelly, is a genus of cyanobacteria found in various environments that forms colonies composed of filaments of moniliform cells in a gelatinous sheath.
Synechococcus is a unicellular cyanobacterium that is very widespread in the marine environment. Its size varies from 0.8 to 1.5 µm. The photosynthetic coccoid cells are preferentially found in well–lit surface waters where it can be very abundant. Many freshwater species of Synechococcus have also been described.
Cyanophages are viruses that infect cyanobacteria, also known as Cyanophyta or blue-green algae. Cyanobacteria are a phylum of bacteria that obtain their energy through the process of photosynthesis. Although cyanobacteria metabolize photoautotrophically like eukaryotic plants, they have prokaryotic cell structure. Cyanophages can be found in both freshwater and marine environments. Marine and freshwater cyanophages have icosahedral heads, which contain double-stranded DNA, attached to a tail by connector proteins. The size of the head and tail vary among species of cyanophages. Cyanophages infect a wide range of cyanobacteria and are key regulators of the cyanobacterial populations in aquatic environments, and may aid in the prevention of cyanobacterial blooms in freshwater and marine ecosystems. These blooms can pose a danger to humans and other animals, particularly in eutrophic freshwater lakes. Infection by these viruses is highly prevalent in cells belonging to Synechococcus spp. in marine environments, where up to 5% of cells belonging to marine cyanobacterial cells have been reported to contain mature phage particles.
Chlamydia is a genus of pathogenic Gram-negative bacteria that are obligate intracellular parasites. Chlamydia infections are the most common bacterial sexually transmitted diseases in humans and are the leading cause of infectious blindness worldwide.
Gloeobacter is a genus of cyanobacteria. It is the sister group to all other cyanbacteria. Gloeobacter is unique among cyanobacteria in not having thylakoids, which are characteristic for all other cyanobacteria and chloroplasts. Instead, the light-harvesting complexes, that consist of different proteins, sit on the inside of the plasma membrane among the (cytoplasm). Subsequently, the proton gradient in Gloeobacter is created over the plasma membrane, where it forms over the thylakoid membrane in cyanobacteria and chloroplasts.
Monera (/məˈnɪərə/) is a biological kingdom that is made up of prokaryotes. As such, it is composed of single-celled organisms that lack a true nucleus.
Cyanobionts are cyanobacteria that live in symbiosis with a wide range of organisms such as terrestrial or aquatic plants; as well as, algal and fungal species. They can reside within extracellular or intracellular structures of the host. In order for a cyanobacterium to successfully form a symbiotic relationship, it must be able to exchange signals with the host, overcome defense mounted by the host, be capable of hormogonia formation, chemotaxis, heterocyst formation, as well as possess adequate resilience to reside in host tissue which may present extreme conditions, such as low oxygen levels, and/or acidic mucilage. The most well-known plant-associated cyanobionts belong to the genus Nostoc. With the ability to differentiate into several cell types that have various functions, members of the genus Nostoc have the morphological plasticity, flexibility and adaptability to adjust to a wide range of environmental conditions, contributing to its high capacity to form symbiotic relationships with other organisms. Several cyanobionts involved with fungi and marine organisms also belong to the genera Richelia, Calothrix, Synechocystis, Aphanocapsa and Anabaena, as well as the species Oscillatoria spongeliae. Although there are many documented symbioses between cyanobacteria and marine organisms, little is known about the nature of many of these symbioses. The possibility of discovering more novel symbiotic relationships is apparent from preliminary microscopic observations.
2-Methylisoborneol (MIB) is an irregular monoterpene derived from the universal monoterpene precursor geranyl pyrophosphate. MIB and the irregular sesquiterpene geosmin together account for the majority of biologically-caused taste and odor outbreaks in drinking water worldwide. MIB has a distinct earthy or musty odor, which most people can easily smell. The odor detection threshold of MIB is very low, ranging from 0.002 to 0.02 micrograms per liter in water. MIB is also a factor in cork taint in winemaking.
Ornithocercus is a genus of planktonic dinoflagellate that is known for its complex morphology that features considerable lists growing from its thecal plates, giving an attractive appearance. Discovered in 1883, this genus has a small number of species currently categorized but is widespread in tropical and sub-tropical oceans. The genus is marked by exosymbiotic bacteria gardens under its lists, the inter-organismal dynamics of which are a current field of research. As they reside only in warm water, the genus has been used as a proxy for climate change and has potential to be an indicator species for environmental change if found in novel environments.
Arthrospira is a genus of free-floating filamentous cyanobacteria characterized by cylindrical, multicellular trichomes in an open left-hand helix. A dietary supplement is made from A. platensis and A. maxima, known as spirulina. The A. maxima and A. platensis species were once classified in the genus Spirulina. Although the introduction of the two separate genera Arthrospira and Spirulina is now generally accepted, there has been much dispute in the past and the resulting taxonomical confusion is tremendous.
Aphanizomenon flos-aquae is a species of cyanobacteria which is commercially processed into a dietary supplement. Aphanizomenon flos-aquae (AFA) is known to contain nutrients including essential fatty acids, active enzymes, vitamins, amino acids, minerals, proteins, complex carbohydrates, and phytochemicals and is marketed as a nutritional supplement.
Planktothrix is a diverse genus of filamentous cyanobacteria observed to amass in algal blooms in water ecosystems across the globe. Like all Oscillatoriales, Planktothrix species have no heterocysts and no akinetes. Planktothrix are unique because they have trichomes and contain gas vacuoles unlike typical planktonic organisms. Previously, some species of the taxon were grouped within the genus Oscillatoria, but recent work has defined Planktothrix as its own genus. A tremendous body of work on Planktothrix ecology and physiology has been done by Anthony E. Walsby, and the 55.6 kb microcystin synthetase gene which gives these organisms the ability to synthesize toxins has been sequenced. P. agardhii is an example of a type species of the genus. P. agardhii and P. rubescens are commonly observed in lakes of the Northern Hemisphere where they are known producers of potent hepatotoxins called microcystins.
Melainabacteria is a phylum related to Cyanobacteria. Organisms belonging to this phylum have been found in the human gut and various aquatic habitats such as groundwater. By analyzing genomes of Melainabacteria, predictions are possible about the cell structure and metabolic abilities. The bacterial cell is similar to cyanobacteria in being surrounded by two membranes. It differs from cyanobacteria in its ability to move by flagella, though some members lack flagella. Melainabacteria are not able to perform photosynthesis, but obtain energy by fermentation.
Trichodesmium thiebautii is a cyanobacteria that is often found in open oceans of tropical and subtropical regions and is known to be a contributor to large oceanic surface blooms. This microbial species is a diazotroph, meaning it fixes nitrogen gas (N2), but it does so without the use of heterocysts. T. thiebautii is able to simultaneously perform oxygenic photosynthesis. T. thiebautii was discovered in 1892 by M.A. Gomont. T. thiebautii are important for nutrient cycling in marine habitats because of their ability to fix N2, a limiting nutrient in ocean ecosystems.
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. 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 during the time period known as the Precambrian time. This suggests that an organism in of the phylum Thermotogae was the most recent common ancestor of modern bacteria.
Richelia is a genus of nitrogen-fixing filamentous heterocystous cyanobacteria. It contains the single species Richelia intracellularis. They exist as both free-living organisms as well as symbionts within potentially up to 13 diatoms distributed throughout the global ocean. As a symbiont, Richelia can associate epiphytically and as endosymbionts within the periplasmic space between the cell membrane and cell wall of diatoms.
Cyanobacteria are a large and diverse phylum of bacteria defined by their unique combination of pigments and their ability to perform oxygenic photosynthesis.
