Cyanobacteria establish symbiosis with plant groups widely spread within the plant kingdom, including fungi lichenized fungi and one non-lichenized fungus, Geosiphon, bryophytes, a water-fern, one gymnosperm group, the cycads, and one flowering plant the angiosperm, Gunnera [2, 35, 36].From Biology of the Nitrogen Cycle, 2007CyanobacteriaSteven L. Percival, David W. Williams, in Microbiology of Waterborne Diseases Second Edition, 2014AbstractCyanobacteria are Gram-negative bacteria. Five types of cyanobacteria have been identified as toxin producers, including two strains of Anabaena flosaquae, Aphanizomenon flosaquae, Microcystis aeruginosa and Nodularia species. Cyanobacterial toxins are of three main types hepatotoxins, neurotoxins and lipopolysaccharide LPS endotoxins. Acute illness following consumption of drinking water contaminated by cyanobacteria is more commonly gastroenteritis. Cyanobacteria are not dependent on a fixed source of carbon and, as such, are widely distributed throughout aquatic environments. These include freshwater and marine environments and in some soils. Direct microscopic examination of bloom material will allow identification of the cyanobacterial species present. Preventing the formation of blooms in the source water is the best way to assure cyanobacteria-free drinking water and membrane filtration technology has the potential to remove virtually any cyanobacteria or their toxins from drinking water. Cyanobacteria have the ability to grow as chapter discusses Cyanobacteria, including aspects of its basic microbiology, natural history, metabolism and physiology, clinical features, pathogenicity and virulence, survival in the environment, survival in water and epidemiology, evidence for growth in a biofilm, methods of detection, and finally, risk full chapterURL Garcia-Pichel, in Encyclopedia of Microbiology Third Edition, 2009IntroductionCyanobacteria constitute a phylogenetically coherent group of evolutionarily ancient, morphologically diverse, and ecologically important phototrophic bacteria. They are defined by their ability to carry out oxygenic photosynthesis water-oxidizing, oxygen-evolving, plant-like photosynthesis. With few exceptions, they synthesize chlorophyll a as major photosynthetic pigment and phycobiliproteins as light-harvesting pigments. All are able to grow using CO2 as the sole source of carbon, which they fix using primarily the reductive pentose phosphate pathway. Their chemoorganotrophic potential is restricted to the mobilization of reserve polymers mainly glycogen during dark periods, although some strains are known to grow chemoorganotrophically in the dark at the expense of external sugars. As a group, they display some of the most sophisticated morphological differentiation among the bacteria, and many species are truly multicellular organisms. Cyanobacteria have left fossil remains as old as 2000–3500 million years, and they are believed to be ultimately responsible for the oxygenation of Earth’s atmosphere. During their evolution, through an early symbiotic partnership, they gave rise to the plastids of algae and higher plants. Today cyanobacteria make a significant contribution to the global primary production of the oceans and become locally dominant primary producers in many extreme environments, such as hot and cold deserts, hot springs, and hypersaline environments. Their global biomass has been estimated to exceed 1015 g of wet biomass, most of which is accounted for by the marine unicellular genera Prochlorococcus and Synechococcus, the filamentous genera Trichodesmium a circumtropical marine form, as well as the terrestrial Microcoleus vaginatus and Chroococcidiopsis sp. of barren lands. Blooms of cyanobacteria are important features for the ecology and management of many eutrophic fresh and brackish water bodies. The aerobic nitrogen-fixing capacity of some cyanobacteria makes them important players in the biogeochemical nitrogen cycle of tropical oceans, terrestrial environments, and in some agricultural lands. Because of their sometimes large size, their metabolism, and their ecological role, the cyanobacteria were long considered algae; even today it is not uncommon to refer to them as blue-green algae, especially in ecological the possible exception of their capacity for facultative anoxygenic photosynthesis, cyanobacteria in nature are all oxygenic photoautotrophs. It can be logically argued that after the evolutionary advent of oxygenic photosynthesis, the evolutionary history of cyanobacteria has been one geared toward optimizing and extending this metabolic capacity to an increasingly large number of habitats. This article provides an overview of the characteristics of their central metabolism and a necessarily limited impression of their diversity. Generalizations might, in the face of such diversity, easily become simplifications. Whenever they are made, the reader is reminded to bear this in full chapterURL ToxinsK. Sivonen, in Encyclopedia of Microbiology Third Edition, 2009Cyanobacteria General DescriptionCyanobacteria are autotrophic microorganisms that have a long evolutionary history and many interesting metabolic features. Cyanobacteria carry out oxygen-evolving, plant-like photosynthesis. Earth’s oxygen-rich atmosphere and the cyanobacterial origin of plastids in plants are the two major evolutionary contributions made by cyanobacteria. Certain cyanobacteria are able to carry out nitrogen fixation. Cyanobacteria occur in various environments including water fresh and brackish water, oceans, and hot springs, terrestrial environments soil, deserts, and glaciers, and symbioses with plants, lichens, and primitive animals. In aquatic environments, cyanobacteria are important primary producers and form a part of the phytoplankton. They may also form biofilms and mats benthic cyanobacteria. In eutrophic water, cyanobacteria frequently form mass occurrences, so-called water blooms. Cyanobacteria were formerly called blue-green algae. Mass occurrences of cyanobacteria can be toxic. They have caused a number of animal poisonings and are also a threat to human full chapterURL Applications in BiotechnologyJay Kumar, ... Ashok Kumar, in Cyanobacteria, 2019AbstractCyanobacteria, the first oxygen-evolving group of photosynthetic Gram-negative prokaryotes, are unique among microbial world and grow in diverse habitats. Cyanobacteria synthesize a vast array of novel secondary metabolites including biologically active compounds with antibacterial, antiviral, antifungal, and anticancer activities. Certain other important metabolites reported from cyanobacteria, include enzymes, toxins, UV-absorbing pigments, and certain fluorescent dyes. Furthermore, biofuel production by cyanobacteria constitutes one of the most promising areas for biotechnological applications. In addition, production of alcohols and isoprenoids, biopolymers, recombinant proteins, and single-cell protein employing modern tools of genetic engineering seems attractive. In the field of agriculture, potent N2-fixing cyanobacteria could be exploited as bio-factory to produce biofertilizer for enriching the fertility of soil. There is a need to develop suitable genome engineering tools in cyanobacteria to produce fuels, value-added compounds, and feedstocks in a sustainable way. In this chapter, an overview of the potential applications of cyanobacteria in various sectors of biotechnology is full chapterURL Biology, Part AThorsten Heidorn, ... Peter Lindblad, in Methods in Enzymology, 2011AbstractCyanobacteria are the only prokaryotes capable of using sunlight as their energy, water as an electron donor, and air as a source of carbon and, for some nitrogen-fixing strains, nitrogen. Compared to algae and plants, cyanobacteria are much easier to genetically engineer, and many of the standard biological parts available for Synthetic Biology applications in Escherichia coli can also be used in cyanobacteria. However, characterization of such parts in cyanobacteria reveals differences in performance when compared to E. coli, emphasizing the importance of detailed characterization in the cellular context of a biological chassis. Furthermore, cyanobacteria possess special characteristics multiple copies of their chromosomes, high content of photosynthetically active proteins in the thylakoids, the presence of exopolysaccharides and extracellular glycolipids, and the existence of a circadian rhythm that have to be taken into account when genetically engineering this chapter, the synthetic biologist is given an overview of existing biological parts, tools and protocols for the genetic engineering, and molecular analysis of cyanobacteria for Synthetic Biology full chapterURL Homeostasis in CyanobacteriaManish Singh Kaushik, ... Arun Kumar Mishra, in Cyanobacteria, 2019AbstractCyanobacteria are a diverse group of Gram-negative oxygenic photoautotrophs and many of them have ability to perform nitrogen fixation in addition to carbon fixation. The demand of iron in cyanobacteria is exceptionally high due to its involvement in the function of a variety of crucial enzymes. Hence, iron acquisition process and its regulation is essential. The Fe2 +/Fe3 + imbalance in the cells causes severe abnormal changes and it needs to be regulated for proper growth and survival of cyanobacteria. Therefore, cyanobacteria have evolved complex metabolic pathways with different mechanisms to regulate intracellular levels of iron for their survival in a changing environment, by tightly regulating iron uptake. In cyanobacteria, iron uptake is regulated by TonB system which includes a barrel-shaped TonB-dependent transporter TBDT, integral membrane protein ExbB, and the membrane-anchored periplasmic protein ExbD. At the center to this regulatory network of iron homeostasis is the ferric uptake regulator Fur, which is a global iron regulator in prokaryotes including cyanobacteria. Considering the importance of availability of iron, understanding the complex iron homeostasis and associated regulatory mechanisms involving Fur is necessary and important. The complex regulatory mechanisms of iron homeostasis along with the basic understanding of the functioning of Fur protein and its interaction with other transcriptional regulator in cyanobacteria have been discussed in this full chapterURL in Nitrogen-Fixing SymbiosesEdder D. Bustos-Díaz, ... Angélica Cibrián-Jaramillo, in Cyanobacteria, 20195 ConclusionsCyanobacteria can form different types of symbiosis with their phyla-rich hosts, making them a wellspring of information for the study of symbiotic nitrogen fixation evolution and origin, and in industrial and agricultural applications. Despite their importance, research of nitrogen fixing symbioses involving cyanobacteria is currently biased toward certain aspects of their biology, and although some species are well understood, others lack basic characterization. This is especially true at the genomic level, in which cyanobacteria remain an undersequenced phylum, and most of the sequenced cyanobacterial genomes to date belong to nonsymbiotic species. The examples provided in this chapter can be a guide to upcoming studies in cyanobacteria genome evolution. The postgenomic era provides tools to carry out such studies. In the framework of comparative evolution, we will be able gain a deeper understanding of cyanobacterial symbiotic diazotrophs from these cyanobacteria and their genomes and begin answering questions such as how these microorganisms evolve, and how they shaped—and still do—the Earth’s full chapterURL Growth-Promoting Abilities in Rai, ... Syiem, in Cyanobacteria, 2019AbstractCyanobacteria blue-green algae are photosynthetic prokaryotes having oxygenic photosynthesis. Several species of cyanobacteria also carry out N2 fixation. They produce a variety of compounds/products useful to mankind. The association of these microorganisms influences plant growth, development, and susceptibility to pathogens. This chapter focuses on their plant growth-promoting are of great use as biofertilizer particularly for the rice crop. Free-living N2-fixing cyanobacteria as well as Azolla a symbiotic association of water fern Azolla and Nostoc/Anabaena are commonly used as biofertilizer for the rice as well as several other crops. In addition, these organisms are also used to improve soil quality, particularly for the reclamation of Usar alkaline soils making them suitable for plant N2-fixing cyanobacteria occur in symbiosis and in associations with a wide spectrum of plants wherein they provide fixed nitrogen directly to the plant partner enabling them to grow in nitrogen-poor soils. In some symbioses, for example in bipartite lichens, cyanobacterial partner provides both fixed-N as well as fixed-C to the plant are also known to excrete a number of other substances that influence plant growth and development. They have been reported to produce growth-promoting regulators resembling gibberellin, cytokinin, abscisic acid, and auxin, vitamins particularly vitamin B, amino acids, polypeptides, and exopolysaccharides that act as antibacterial, antifungal, and toxin-like substances. Cyanobacteria also have the ability to mobilize insoluble organic phosphates for the benefit of the crop full chapterURL in Diverse HabitatsLira A. Gaysina, ... Prashant Singh, in Cyanobacteria, 2019AbstractCyanobacteria are an enormously diverse group of prokaryotes whose adaptive capacity along with the ability to tolerate extreme conditions makes them omnipresent. They are found in almost all the habitats of the Earth where life can be imagined to have flourished. Cyanobacteria are present in a wide range of habitats viz. marine, freshwater, soil, biological soil crusts, snow, cryoconites, etc. Further, they are found in symbiotic association with different hosts and also occur in extreme stressed conditions like volcanic ash, salted soils, and anthropogenically disturbed areas. This chapter explores the diversity of cyanobacteria from different habitats and enlists the dominant groups inhabiting these habitats. The diversity of cyanobacteria from different climatic zones; temperate, tropical as well as Polar Regions have been reviewed and documented in this chapter. The taxonomic complexity of cyanobacteria has hindered the capture of the actual biodiversity which is evident from the fact that the reported diversity encompasses only the traditional cyanobacterial genera. Morphological plasticity, ecological flexibility, and huge amount of heterogeneity are responsible for the confusions surfacing the cyanobacterial taxonomy. In this chapter, we also discuss the current trends in cyanobacterial taxonomy which would be essential in the studies conducted to capture the biodiversity of cyanobacteria from different full chapterURL Pathways and Environmental Responses in Plants Part AAnnesha Sengupta, ... Himadri B. Pakrasi, in Methods in Enzymology, 20224 SummaryCRISPR-Cas is a revolutionary technology that has been borrowed from the bacterial system to be modified and used for editing genome, modulating gene expression and containing genetically modified strains. The antibiotic markerless engineering and the ability to simultaneously target polyploid genome have made CRISPR-Cas technique attractive for multi-genome organisms, like cyanobacteria. Cas12a/Cas9-mediated genome engineering has become widely popular in cyanobacteria. However, these techniques in their current form are limited in cyanobacteria for deleting large genomic regions, genome engineering of novel cyanobacteria where the cellular machinery is not well exploited, gene activation, repression of genes part of the operon, and efficient point are a complex set of organisms that exhibit various fascinating features and therefore implementing these novel Cas proteins and technologies for genome engineering will truly help understand the complexity of these photoautotrophs and gear toward developing these strains as carbon negative cellular factories; however, there are still several challenges we are facing with this technology in a long DNA fragment > 110 kb deletion has been succeeded in Anabaena 7120 Niu et al., 2019, other cyanobacterial species need to be validated. And more importantly, insertion of a long DNA fragment > 50 kb into the chromosome has never been proved in cyanobacteria. Success to delete and insert long fragment efficiently and robustly will ease the synthetic biology and pathway engineering applications in realize that synthetic biology tools are still the key limiting factor for engineering work in cyanobacteria, such as promoters, ribosome binding sites, and terminators. For most of cyanobacteria, a tight, broad range, and robust inducible promoter is still not available. Establish a library containing various bio-bricks is very useful for further gene repression by CRISPRi, the gene located in the operon is always difficult to design the gRNA. Repressing on the first gene of an operon will generate the polar effect, while if the target gene is not the first gene, the repressing level sometimes is the Cas9 and Cas12a proteins and only CRISPR and CRISPRi technologies have been explored in cyanobacteria. So other Cas proteins with various functions are of great interest to test, which should facilitate the genetic work in cyanobacteria with specific purposeRead full chapterURL