Phycosphere

The phycosphere is a microscale mucus region that is rich in

environmental factors.^[2]

In terms of comparison, the phycosphere in

, which is the root zone important for nutrient recycling. Both plant roots and phytoplankton exude chemicals which alter their immediate surrounds drastically – including altering the pH and oxygen levels. In terms of community construction, chemotaxis is used in both environments in order to propagate the recruitment of microbes. In the rhizosphere, chemotaxis is used by the host – the plant – to mediate the motility of the soil which allows for microbial colonization. In the phycosphere, the phytoplankton release of specific chemical exudates elicits a response from bacterial symbionts who exhibit chemotaxis signaling, thereby enabling the recruitment of microbes and subsequent colonization. The interfaces also have a few similar microbes, chemicals, and metabolites involved in the host – symbiont interactions. This includes microbes such as Rhizobium, which in the phycospheres of green algae was found to be the foremost microbe when compared to other abundant community members. Chemicals such as dimethylsuloniopropionate (DMSP) and 2,3-dihydroxypropane-1-sulfonate (DHPS) and metabolites such as sugars and amino acids are implicated in the mechanisms of action of both microbiomes.

Phytoplankton-bacteria interactions

The

microscale interactions between the phytoplankton and bacteria are complex. The phytoplankton-bacteria interactions have the potential to be parasitism, competition or mutualism

.

Interactions between phytoplankton and bacteria in the phycosphere could be potentially important in low-nutrient regions of the ocean and an example of mutualism. In marine

oligotrophic

regions and the bacteria rely on organic matter surrounding the phycosphere for a source of food.

However, bacterial-phytoplankton interactions in the phycosphere could be

antibiotics. The bacteria, who are also food stressed, could kill the phytoplankton and use it as a food substrate.^[4]

Also,

acidic. (See also eutrophication

).

Examples of bacteria associated with phycosphere

In reality, the actual

genera

associated with the phycosphere.

Pseudomonas
Achromobacter
Roseobacter
Flavobacteraceae
Alteromonadaceae
Athrospira plantensis
Terrimonas rubra
C.vulgaris
Sediminibacterium
Chryseobacterium

References

ISBN 978-0-471-48529-2
.

S2CID 21278078
.

doi:10.1146/annurev.es.13.110182.001451
.

S2CID 10055219
.

5. Seymour, Justin R., et al. “Zooming in on the Phycosphere: the Ecological Interface for Phytoplankton–Bacteria Relationships.” Nature Microbiology, vol. 2, no. 7, 2017, pp. 1–13., doi:10.1038/nmicrobiol.2017.65.
6. Kim, B.-H., Ramanan, R., Cho, D.-H., Oh, H.-M., & Kim, H.-S. (2014). Role of Rhizobium, a plant growth promoting bacterium, in enhancing algal biomass through mutualistic interaction. Biomass and Bioenergy, 69, 95–105. doi: 10.1016/j.biombioe.2014.07.015
7. Geng, H., & Belas, R. (2010). Molecular mechanisms underlying roseobacter–phytoplankton symbioses. Current Opinion in Biotechnology, 21(3), 332–338. doi: 10.1016/j.copbio.2010.03.013 8. Ramanan, R., Kang, Z., Kim, B.-H., Cho, D.-H., Jin, L., Oh, H.-M., & Kim, H.-S. (2015). Phycosphere bacterial diversity in green algae reveals an apparent similarity across habitats. Algal Research, 8, 140–144. doi: 10.1016/j.algal.2015.02.003
9. Scharf, B. E., Hynes, M. F., & Alexandre, G. M. (2016). Chemotaxis signaling systems in model beneficial plant–bacteria associations. Plant Molecular Biology, 90(6), 549–559. doi: 10.1007/s11103-016-0432-4

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[1] ISBN 978-0-471-48529-2
.

[2] S2CID 21278078
.

[3] :10.1146/annurev.es.13.110182.001451
.

[4] S2CID 10055219
.

[2]

[4]