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Original 'Microbial Cooperation'

Mutualism

Perhaps the most common cooperative interactions seen in microbial systems are mutually beneficial (+/+). Mutually beneficial social interactions provide a direct fitness benefit to the individual that performs the behavior, which outweighs the cost of performing the behavior. Most of the time, individuals partaking in the behaviors have a shared interest in cooperation. In microbial systems, this is most often seen as the production of public goods. Many microbes, especially bacteria, produce numerous factors that are released into the environment beyond the cell membrane.

One very popular example of mutually beneficial microbial interactions involves the production of siderophores. Siderophores are iron-scavenging molecules produced by many microbial taxa, including bacteria and fungi. Iron is a major limiting factor for bacterial growth because most iron in the environment is in the insoluble Fe(III) form. In order for bacteria to access this limiting factor, cells will manufacture these enzymes, and then secrete them into the extracellular space. Once released, the siderophore will sequester the iron, making it metabolically accessible for the bacteria.

There are many explanations in place that justify the evolution of mutually beneficial interactions. Most importantly, in order for the production of public goods to be evolutionarily beneficial, the behavior must provide a direct benefit to the reproductive performance of the actor that outweighs the cost of performing the behavior. While a siderophore is meant to benefit the cell that secretes it, this is not a guarantee. Rather, any cell that encounters the siderophore can access the iron. Therefore, this strategy will only be evolutionary sound if all cells in a given population secrete siderophores, and thus all cells in that population will share the cost and benefit of siderophore production.

Edit 'Microbial Cooperation'

Mutualism

Perhaps the most common cooperative interactions seen in microbial systems are mutually beneficial (+/+). Mutually beneficial social interactions provide a direct fitness benefit to both individuals involved, while outweighing any cost of performing the behavior.^[3] In an environment with individual microbes, mutualism is most often performed in order to increase individual fitness benefit. However, in a community, microorganism will interact on a large scale to allow for the persistence of the population, which thereby will increase their own fitness.^[6]

Most of the time, individuals partaking in the behaviors have a shared interest in cooperation. In microbial systems, this is most often seen as the production of public goods, metabolically expensive molecules, which are produced for an individual, but may also be used by neighbouring organisms. Many microbes, especially bacteria, produce numerous factors that are released into the environment beyond the cell membrane.

One very popular example of mutually beneficial microbial interactions involves the production of siderophores. Siderophores are iron-scavenging molecules produced by many microbial taxa, including bacteria and fungi. These molecules play a role in facilitating the uptake and metabolism of iron in the environment, as it normally exists in an insoluble form. ^[5] In order for bacteria to access this limiting factor, cells will manufacture these enzymes, and then secrete them into the extracellular space.^[4a] Once released, the siderophore will sequester the iron, making it metabolically accessible for the bacteria. The production of siderophores is often used as an example of mutualism as the compounds are not constricted to individual usage, and can be taken up by any neighbouring bacteria.

There are many explanations in place that justify the evolution of mutually beneficial interactions. Most importantly, in order for the production of goods to be evolutionarily beneficial, the behavior must provide a direct benefit to the reproductive performance of the actor that outweighs the cost of performing the behavior.^[5] This is most often seen in the case of direct fitness benefit. As bacteria are most often found in colonies, neighbouring bacteria are likely to express genetic commonality. Therefore, by increasing the chances for a nearby bacterium to grow and divide, the host is increasing their own passage of genetic material. In the case of siderophores for example, the compounds are not secreted at random by the host microorganism. The bacteria have developed a method of sensing if a related bacterium is nearby, and will then increase its production of siderophores.^[4b]This is done in order to increase the fitness advantage of microorganisms that share genes.

[4]: West SA, Buckling A. 2003. Cooperation, virulence and siderophore production in bacterial parasites. Proc. R. Soc. Lon. Ser. B 270:37–44.

[5]: Neilands JB. Siderophores 1995. Structure and function of microbial iron transport compounds. J. Biol. Chem. 270:26723–6. 7.

[6]: Guimarães, P. R., Pires, M. M., Marquitti, F. M. and Raimundo, R. L. 2016. Ecology of Mutualisms. eLS. 1–9.

Sddem (talk) 22:59, 8 October 2017 (UTC)

Final Edit 'Microbial Cooperation'

Mutualism

Perhaps the most common cooperative interactions seen in microbial systems are mutually beneficial (+/+). Mutually beneficial social interactions provide a direct fitness benefit to both individuals involved, while outweighing any cost of performing the behaviour.^[3] In an environment with individual microbes, mutualism is most often performed in order to increase individual fitness benefit. However, in a community, microorganisms will interact on a large scale to allow for the persistence of the population, which will thereby increase their own fitness.

The majority of the time, organisms partaking in these behaviours have a shared interest in cooperation. In microbial systems, this is often seen in the production of metabolically expensive molecules, known as public goods. Many microbes, especially bacteria, produce numerous public goods that are released into the extracellular environment. The diffusion that occurs allows for them to be used by neighbouring organisms, despite being produced for the individual.

One very popular example of mutually beneficial microbial interactions involves the production of siderophores. Siderophores are iron-scavenging molecules produced by many microbial taxa, including bacteria and fungi. These molecules are known as chelating agents and play an important role in facilitating the uptake and metabolism of iron in the environment, as it normally exists in an insoluble form.^[5] In order for bacteria to access this limiting factor, cells will manufacture these molecules, and then secrete them into the extracellular space.^[4a] Once released, the siderophores will sequester the iron, and form a complex, which is recognized by bacterial cell receptors. It can then be transported into the cell and reduced, making the iron metabolically accessible for the bacteria. The production of siderophores is often used as an example of mutualism as the compounds are not constricted to individual usage. As long as the organism possesses a receptor for the siderophore-Fe (III) complex, they can be taken up and utilized.^[7]

There are many explanations in place that justify the evolution of mutually beneficial interactions. Most importantly, in order for the production of public goods to be evolutionarily beneficial, the behaviour must provide a direct benefit to the reproductive performance of the actor that outweighs the cost of performing the behaviour.^[5] This is most often seen in the case of direct fitness benefit. As bacteria are most often found in colonies, neighbouring bacteria are likely to express genetic commonality. Therefore, by increasing the chances for a nearby bacterium to grow and divide, the host is increasing their own passage of genetic material. In the case of siderophores, a positive correlation was found between relatedness among bacterial lineages and siderophore production ^[4b] .

Microbial communities are not only interested in the survival and productivity of their own species, however. In a mixed community, different bacterial species have been found to adapt to different food sources, including the waste products of other species, in order to stave off unnecessary competition.^[8] This allows heightened efficiency for the community as a whole.

Having a balanced community is very important for microbial success. In the case of siderophore production, there must be equilibrium between the microbes that spend their energy to produce the chelating agents, and those that can utilize xenosiderophores.  Otherwise, the exploitative microbes would eventually out-compete the producers, leaving a community with no organisms able to produce siderophores, and thus, unable to survive in low iron conditions. This ability to balance between the two populations is currently being researched. It is thought to be due to the presence of low-affinity receptors on the non-producers, or producers generating a toxin-mediated interference mechanism.^[9]

3.  Sachs JL et al. 2004. The Evolution of Cooperation. The Quarterly Review of Biology 79:135-160. doi: 10.1128/mBio.00099-12

4. West SA, Buckling A. 2003. Cooperation, virulence and siderophore production in bacterial parasites. Proc. R. Soc. Lon. Ser. B 270:37–44. doi: 10.1098/rspb.2002.2209

5. Neilands JB. Siderophores 1995. Structure and function of microbial iron transport compounds. J. Biol. Chem. 270:26723–6. 7. doi: 10.1074/jbc.270.45.26723

6. Guimarães, P. R., Pires, M. M., Marquitti, F. M. and Raimundo, R. L. 2016. Ecology of Mutualisms. eLS. 1–9. doi: 10.1002/9780470015902.a0026295

7. Miethke, M., Marahiel M. A., 2007. Siderophore-Based Iron Acquisition and Pathogen Control. Microbiol. Mol. Biol. Rev. 71:413-451. doi: 10.1128/MMBR.00012-07

8. Lawrence, D. et al. 2010. Species Interactions Alter Evolutionary Responses to a Novel Environment. PLOS. Bio. doi: https://doi.org/10.1371/journal.pbio.1001330

9. Butaitė, E., et al. 2017. Siderophore cheating and cheating resistance shape competition for iron in soil and freshwater Pseudomonascommunities. Nat. Commun. 8. doi: 10.1038/s41467-017-00509-4

Sddem (talk) 00:36, 20 November 2017 (UTC)