Microbial ecology

Microbial ecology

Microbial ecology is the ecology of microorganisms: their relationship with one another and with their environment. It concerns the three major domains of life — Eukaryota, Archaea, and Bacteria — as well as viruses.

Microorganisms, by their omnipresence, impact the entire biosphere. Microbial life plays a primary role in regulating biogeochemical systems in virtually all of our planet's environments, including some of the most extreme, from frozen environments and acidic lakes, to hydrothermal vents at the bottom of deepest oceans, and some of the most familiar, such as the human small intestine.[1][2] As a consequence of the quantitative magnitude of microbial life (Whitman et al. (1998) calculated 5 × 10 30 cells, eight orders of magnitude greater than the number of stars in the observable universe [3][4] ) microbes, by virtue of their biomass alone, constitute the single largest carbon sink.[5] Aside from carbon fixation, microorganisms’ key collective metabolic processes (including nitrogen fixation, methane metabolism, and sulfur metabolism) control global biogeochemical cycling.[6] The immensity of microorganisms’ production is such that, even in the total absence of eukaryotic life these processes would likely continue unchanged.[7]



Microbes, especially bacteria, often engage in symbiotic relationships (either positive or negative) with other organisms, and these relationships affect the ecosystem. One example of these fundamental symbioses are chloroplasts, which allow eukaryotes to conduct photosynthesis. Chloroplasts are considered to be endosymbiotic cyanobacteria, a group of bacteria that are thought to be the origins of aerobic photosynthesis. Some theories state that this invention coincides with a major shift in the early earth's atmosphere, from a reducing atmosphere to an oxygen-rich atmosphere. Some theories go as far as saying that this shift in the balance of gasses might have triggered a global ice-age known as the Snowball Earth.


They are the backbone of all ecosystems, but even more so in the zones where light cannot approach and thus photosynthesis cannot be the basic means to collect energy. In such zones, chemosynthetic microbes provide energy and carbon to the other organisms.

Other microbes are decomposers, with the ability to recycle nutrients from other organisms' waste poducts. These microbes play a vital role in biogeochemical cycles [5]. The nitrogen cycle, the phosphorus cycle and the carbon cycle all depend on microorganisms in one way or another. For example, nitrogen which makes up 78% of the planet's atmosphere is "indigestible" for most organisms, and the flow of nitrogen into the biosphere depends on a microbial process called fixation.

Due to the high level of horizontal gene transfer among microbial communities,[8] microbial ecology is also of importance to studies of evolution.[9]

Microbial resource management

Biotechnology may be used alongside microbial ecology to address a number of environmental and economic challenges. Managing the carbon cycle to sequester carbon dioxide and prevent excess methanogenesis is important in mitigating global warming, and the prospects of bioenergy are being expanded by the development of microbial fuel cells. Microbial resource management advocates a more progressive attitude towards disease, whereby biological control agents are favoured over attempts at eradicationJ. Fluxes in microbial communities has to be better characterized for this field's potential to be realised.[10] In addition, there are also clinical implications, as marine microbial symbioses are a valuable source of existing and novel antimicrobial agents, and thus offer another line of inquiry in the evolutionary arms race of antibiotic resistance, a pressing concern for researchers [11].

See also


  1. ^ Bowler, C.; D. M Karl, R. R Colwell (2009). "Microbial oceanography in a sea of opportunity". Nature 458 (7244): 180–184. 
  2. ^ Konopka, Allan (2009-11). "What is microbial community ecology?". The ISME Journal 3 (11): 1223-1230. doi:10.1038/ismej.2009.88. ISSN 1751-7370. http://www.ncbi.nlm.nih.gov/pubmed/19657372. Retrieved 2011-02-27. 
  3. ^ Whitman, W B; D C Coleman, W J Wiebe (1998-06-09). "Prokaryotes: the unseen majority". Proceedings of the National Academy of Sciences of the United States of America 95 (12): 6578-6583. ISSN 0027-8424. http://www.ncbi.nlm.nih.gov/pubmed/9618454. Retrieved 2011-02-27. 
  4. ^ "number of stars in the observable universe - Wolfram". http://www.wolframalpha.com/input/?i=number+of+stars+in+the+observable+universe. Retrieved 2011-11-22. 
  5. ^ a b Fenchel, Tom (1998). Bacterial biogeochemistry : the ecophysiology of mineral cycling (2nd ed. ed.). San Diego: Academic Press. 
  6. ^ DeLong, Edward F. (2009-05). "The microbial ocean from genomes to biomes". Nature 459 (7244): 200–206. doi:10.1038/nature08059. ISSN 0028-0836. 
  7. ^ Lupp, Claudia (2009-05). "Microbial oceanography". Nature 459 (7244): 179. doi:10.1038/459179a. 
  8. ^ McDaniel, Lauren D.; Elizabeth Young, Jennifer Delaney, Fabian Ruhnau, Kim B. Ritchie, John H. Paul (2010-10-01). "High Frequency of Horizontal Gene Transfer in the Oceans". Science 330 (6000): 50. doi:10.1126/science.1192243. 
  9. ^ Smets, B. F; T. Barkay (2005). "Horizontal gene transfer: perspectives at a crossroads of scientific disciplines". Nature Reviews Microbiology 3 (9): 675–678. 
  10. ^ W. Verstraete (May 2007). "Microbial ecology and environmental biotechnology". Isme J. 1 (1): 4–8. doi:10.1038/ismej.2007.7. PMID 18043608. 
  11. ^ Ott, J. (2005). "Marine Microbial Thiotrophic Ectosymbioses". Oceanography and marine biology. 42: 95–118. 

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