It gives a comprehensive overview of algal and cyanobacteria symbioses, including Gagat); The Azolla–Anabaena–Bacteria Association: A Case of Symbiotic Abduction? (Francisco Carrapiço); Symbiosis Between Green Algae and Hydra. Feb 24, Discusses parasitic and mutualistic relationships of fungi. A mycorrhiza is a mutualistic relationship between a fungus and a plant. The fungus grows in or The fungus grows around the bacterial or algal cells. The fungus. To completely understand the ecophysiology and symbiosis between algae and . Algal–bacterial interactions cover the whole range of symbiotic relationships.
The oxygen atmosphere that we depend on was generated by numerous cyanobacteria during the Archaean and Proterozoic Eras. Before that time, the atmosphere had a very different chemistry, unsuitable for life as we know it today.
The other great contribution of the cyanobacteria is the origin of plants. The chloroplast with which plants make food for themselves is actually a cyanobacterium living within the plant's cells. Sometime in the late Proterozoic, or in the early Cambrian, cyanobacteria began to take up residence within certain eukaryote cells, making food for the eukaryote host in return for a home.
This event is known as endosymbiosis, and is also the origin of the eukaryotic mitochondrion. Because they are photosynthetic and aquatic, cyanobacteria are often called "blue-green algae".
This name is convenient for talking about organisms in the water that make their own food, but does not reflect any relationship between the cyanobacteria and other organisms called algae.
Introduction to the Cyanobacteria
Cyanobacteria are relatives of the bacteria, not eukaryotes, and it is only the chloroplast in eukaryotic algae to which the cyanobacteria are related. Click on the buttons below to find out more about the Cyanobacteria. Mutualism Mutualism is a biologic interaction in which two or more partners of different species benefit each other [ 6812 ].
A typical example of mutualism is that a bacterial species supplies vitamin B12 to an algal partner in exchange for fixed carbon [ 1317 ]. However, mutualism is not only limited to micronutrient supply from bacteria [ 18 ], as there are studies highlighting the role of Azospirillum, Mesorhizobium and Rhizobium sp.
Such exchanges between biotic communities in aquatic ecosystems have a huge role in cycling of nitrogen, sulphur, carbon and phosphorus [ 22232425262728 ].
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Commensalism Commensalism is a relationship in which only one partner benefits. Commensals could be considered as non-interacting partners [ 29 ]. Microorganisms that belong to the phycosphere represent a bacterial diversity dwelling on the algal surface [ 21 ]. However, there is a very faint line that separates mutualism and commensalism, and even parasitism, and environmental factors may shift an interaction from one type to another.
Introduction to the Cyanobacteria
In this sense, there are studies that partially demonstrate the role of nutrient availability, N: P ratio and light intensity in the shift from mutualism to parasitism and vice versa via commensalism, although the mechanisms behind such shifts still remain unclear [ 1230 ]. The interaction between Chlamydomonas reinhardtii and heterotrophic bacteria is another example of commensalism.
Parasitism Parasitism is a well-studied interaction in which one species benefits at the expense of the other and exerts negative effects on it. Normally, the parasite is smaller in size and needs the host to be alive. Many bacteria are known to negatively affect algae, and, therefore, they have been proposed as microalgae and cyanobacterial bloom controlling microorganisms [ 313233 ].
In the case of bacterial parasitism on algae, the algal cell is lysed by the action of glucosidases, chitinases, cellulases and other enzymes [ 3336 ].
Once the algal cell is lysed, the bacteria can use intracellular algal compounds as nutrients. However, there is one more form of parasitism, where a competition for existing nutrients occurs that results in slower growth rates of algae [ 12 ]. An apparent or incidental altruism has recently been reported, in which an individual acts for the exclusive benefit of another; and it can be self-driven or driven by the beneficiary [ 37 ].
We speculate that such an altruistic relationship might also be taking place in some of the bacterial-microalgal consortia.
Symbiotic bacteria - Wikipedia
In general, most of these associations usually occur in close proximities. For example, the parasitic bacteria are usually present near the algal cell wall to facilitate its degradation [ 33 ] and the habitats play an important role in the ecophysiology of these organisms. Parasites in general have wide-ranging applications in industrial biotechnology. For example, microbial cellulases, hemicelluloses and pectinases, obtained from such parasites, are currently being used in food, brewery, wine, textile and paper industries, among others [ 38 ].
Chitinolytic enzymes are also used for the preparation of pharmaceutical oligosaccharides and for control of pathogenic microorganism transmission [ 39 ].
In summary, a variety of interactions between algae and bacteria have been described, which can range from beneficial to detrimental to algal growth.
The control of some of these interactions may serve as a highly useful tool to either stimulate the production of a given microalgal species, to control algal blooms, or to even harvest algal biomass at a low cost. Effects on Biomass Production Traditionally, efforts have been paid to obtain axenic algal monocultures for developing biomass production processes. However, it is nowadays recognized that the interactions between microalgae and microorganisms have potential, with special applicability in aquaculture, to improve algal biomass production and to enrich this biomass with compounds of industrial interest such as lipids and carbohydrates.
In this respect, the general bacterial attributes that may be of interest in the interaction with microalgae, and which might affect their growth, include motility, chemotaxis, type IV secretion systems, quorum sensing systems and synthesis of growth promoters [ 40 ].
Figure 1 summarizes some of the main chemical mediators so far reported, which regulate the interactions between microalgae and bacteria and some of the potential applications derived from such interactions.lichens : Symbiotic Association between Algae and Fungi