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This picture represents the changes that have resulted from evolution. Evolution is the slow change of living things over time.

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Cyanobacteria are a type of photosynthetic prokaryotes. Formerly known as "blue-green algae"

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Abstract

Cyanobacteria 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 biofilms.

This 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 assessment.

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URL: https://www.sciencedirect.com/science/article/pii/B9780124158467000056

Cyanobacteria (also called blue-green algae) are an ancient group of photosynthetic microbes that occur in most inland waters and that can have major effects on the water quality and functioning of aquatic ecosystems. They include about 2000 species in 150 genera, with a wide range of shapes and sizes. Cyanobacteria have a variety of cell types, cellular structures, and physiological strategies that contribute to their ecological success in the plankton, metaphyton, or periphyton. They are of special interest to water quality managers because many produce taste and odor compounds, several types of toxins, and noxious blooms. Ecologically, the three most important groups of cyanobacteria found in inland waters are mat-formers, which form polysaccharide-rich crusts, films, and thicker layers over rocks, sediments, and plants; bloom-formers, which occur in eutrophic lakes and cause food web disruption as well as produce toxins and surface scums; and picocyanobacteria, minute species that are often the main photosynthetic cell type in oligotrophic (nutrient-poor) lakes and their microbial food webs. Additional ecological groups include the metaphyton that is loosely associated with emergent macrophytes; colonial aggregates of cyanobacteria that are common in mesotrophic waters; and various symbiotic associations. Several inland water species of cyanobacteria are harvested or cultivated as food sources, animal feeds, fertilizers, and health products.

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Introduction

Cyanobacteria 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 CO ₂ 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 10 ¹⁵ 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 studies.

With 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 mind.

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Introduction

Cyanobacteria Stanier ex Cavalier-Smith (or cyanoprokaryotes, or, formerly, blue-green algae, cyanophyceae, myxophyceae, calcibionta, and calcimicrobes) are a phylum of phototrophic Prokaryota. They were fundamentally important in Earth history, as primary producers and on the progressive atmospheric oxygenation. Moreover, they have possibly invented the heterotrophy, cannibalism, specialized structures involved in the reproduction, and death. Currently, the classifications of the cyanobacteria intent to combine molecular phylogenetic and paleontological data, in order to elucidate the macroevolution of the group; especially, the etaps during which filamentous cyanobacteria evolved to some degree of cell differentiation, giving rise to specialized cells for nitrogen fixation (heterocysts) and resting cells able to endure environmental stress (akinetes). Fossil akinetes have been identified at 1650-1400 Ma in cherts from Siberia, China, and Australia, and perhaps as early as 2100 Ma in cherts from West Africa.

Cyanobacteria were always hard to be classified, and the recent classifications were revised, based on molecular sequence data. Generally, classifications subdivide Cyanobacteria into five orders: order I Chroococcales, order II Pleurocapsales, order III Oscillatoriales, order IV Nostocales, order V Stigonematales. Among these orders, Chroococcales (I) and Oscillatoriales (III) are probably polyphyletic; the monophyly of Pleurocapsales (II) is discussed; whereas Nostocales (IV) and Stigonematales (V) were found to be monophyletic; moreover, all the cyanobacteria with heterocysts evolved from a common ancestor.

The fossil, cyanobacterial textures encompass: (1) isolated, coccoid, calcified cells; (2) tubular filaments eventually with pseudoramifications, or true bifurcations; (3) bioconstructions of types stromatolite, oncoids, microbialites or dendrolites, with binding and trapping of carbonate at the surface of mats; (4) nodular colonies composed of single to bifurcated spans of filaments. Due to the complexification from coccoid individuals to hemispherical colonies of bifurcated filaments, it is possible to speculate that the macroevolution of the calcified cyanobacteria was as follows (Fig. 1): (1) coccoid thalli (incerti ordinis 1; probably Chroococcales); (2) filamentous and/or coccoid, stromatolitic and microbialitic taxa (incerti ordinis 2: stromatolites sensu lato); (3) carbonate stromatolitic textures (incerti ordinis 3; family Aphralysiaceae); (4) colonial coccoid textures (incerti ordinis 4; family Chabakoviaceae); (5) tubular, single filaments (order Proauloporales or Oscillatoriales; family Girvanellaceae); (6) colonial groups of filaments (order Proauloporales or Oscillatoriales; family Garwoodiaceae).

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URL: https://www.sciencedirect.com/science/article/pii/B9780124095489118433

Minimum Database and Confirmatory Tests

As with other suspect cyanobacteria intoxications, algal identification in water samples or in samples collected from the animal's skin or gastric contents greatly assists with the diagnostic workup. Algal-containing samples should be chilled, not frozen, preserved in 10% formalin (v/v 50:50), and submitted to a phycologist for identification. As toxicity of cyanotoxins is strain-specific, positive identification does not predict the hazard level.

Anatoxin-a, homoanatoxin-a, and anatoxin-a(s) poisonings do not result in specific changes in serum chemistry parameters. In fact, because of the rapid progression and death with these neurotoxins, blood work is rarely performed. If available, possible nonspecific changes are hyperglycemia, acidosis, mild hypophosphatemia, and mild respiratory alkalosis. In cases of anatoxin-a(s) poisoning, a depressed blood cholinesterase activity along with an adequate brain cholinesterase activity supports the diagnosis.

Toxicologic analyses for algal toxins in biologic specimens are recommended to establish a diagnosis. Anatoxin-a can be analyzed by liquid chromatography and tandem mass spectrometry in algal material, water, gastrointestinal contents, urine, and bile. Select veterinary toxicology laboratories can perform analysis of biologic specimens for anatoxin-a(s).

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URL: https://www.sciencedirect.com/science/article/pii/B9781455707171000430

Cyanobacteria: General Description

Cyanobacteria 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 health.

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1.6.1 What Is Blue-Green Algae?

Blue-green algae (BGA), also known as cyanobacteria, can range in colors from blues, greens, reds, and black. BGA can reduce nitrogen and carbon in water, but can also deplete dissolved oxygen when overabundant. Monitoring BGA is important because they pose a serious threat to water quality, ecosystem stability, surface drinking water supplies, and public health through toxin production and the large biomass produced in algal blooms.

YSI measures blue-green algae in real time through the in vivo fluorometry (IVF) technique. This method directly detects the fluorescence of a specific pigment in living algal cells and determines relative algal biomass. The BGA sensor does not receive interference from chlorophyll or turbidity.

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Abstract

Cyanobacteria, previously known as blue-green algae, are photosynthetic microorganisms that are abundant in nature. Some cyanobacteria have been consumed by humans for centuries while others are known for their toxicity. The initial metabolic products of photosynthesis are sugar phosphates. Excess photosynthates in cyanobacteria are stored as polysaccharides (primarily glycogen) and may constitute up to 60% of the biomass. Thus cyanobacteria have a natural potential to produce sugars from photosynthesis using CO ₂ as the sole carbon source. Although cyanobacteria produce a limited number of sugar compounds naturally, genetic engineering can increase the diversity of produced sugars, as well as increase the production yield. Sucrose, fructose, glucose, glycerol, erythritol, and mannitol have been produced in genetically engineered cyanobacteria, although the yields need to be improved before these are of practical significance. It is possible that these and other more valuable simple sugar compounds, such as mannose, fucose, tagatose, and l-sugars can be produced in cyanobacteria on a commercially relevant scale.

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URL: https://www.sciencedirect.com/science/article/pii/B9780128115190000029

4.8.5.2.1.3 Climate impact

Cyanobacteria are a type of prokaryote. Outbreaks only occur when the population of cyanobacteria per unit of water increases drastically. The growth profile of cyanobacteria presents an S-shape curve, which indicates that a certain amount of time is needed for single cells and groups to develop. Environmental conditions, especially water temperature, significantly impact their growth rate. Cyanobacteria tend to become overpopulated at certain temperatures. Otherwise, the growth rate is inhibited and the population size remains low. In this way, climate plays an important role in early period of cyanobacteria growth. Zheng et al. (2008) reported that cyanobacteria outbreaks readily occurred over periods of 30 days during which sufficient nutrients were available, temperature remained above 18 °C, active accumulated temperature remained above 370 °C·d, weak wind conditions, and more than 208 h of sunlight. However, climate conditions such as high relative humidity, precipitation, and wind speed do not influence cyanobacteria outbreaks remarkable. Generally, July and August in the Taihu lake basin is usually favorable to cyanobacteria outbreaks.

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Abstract

Cyanobacteria, 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 N ₂-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 presented.

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URL: https://www.sciencedirect.com/science/article/pii/B9780128146675000167

# data[].attributes.attachment_link.description
Cyanobacteria 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.