Bacteria

Bacteria are prokaryotic, single-celled, usually microscopic organisms, smaller than eukaryotic cells.

Despite being single-celled organisms, bacteria can communicate with one another via a process known as quorum sensing.

Quorum sensing (QS) is a bacterial cell-cell communication process that involves the production, detection, and response to extracellular signalling compounds known as autoinducers (AIs).

Through this mechanism, they can form and function as multicellular population.

Basic quorum sensing: How bacteria know who’s around them. (Nidhi Srivaths)

Classification is the division of organisms into distinct categories based on morphological similarity or evolutionary links.

Bacteria are classified based on shape, temperature requirements, oxygen requirements, cell wall and staining reaction, salt tolerance, nutritional requirements, ability to form spores, the basis of capsule, pH requirements, presence and type of flagella.

We give you some examples of classification

Based on Shape:

Presence and type of flagella

Temperature requirements

Bacteria and humans

Commensals- Referred to as "normal flora" these bacteria usually cause no harm e.g. Escherichia coli

Predators- Some bacteria species kill and then devour other microorganisms

Mutualists- Bacteria that create intimate spatial relationships in order to survive.

For example, all animals need vitamin B12, but they can't produce it so they really on bacteria and some archaea (we will talk about archaea soon) that possess the genes and enzymes necessary to synthesize vitamin B12.

Pathogens- Bacteria that create parasitic associations with other organisms. Pathogenic bacteria produce infections and are a major cause of human death and disease.

Did you know?

There are bacteria capable of reaching sizes just visible to the naked eye.

Epulopiscium fishelsoni

Thiomargarita namibiensis

References

1. D.A. Arokkiam. (2021, April 20). Microbe but not microscopic!!! - Botany Boost Blog. Botany Boost Blog. https://fos.cmb.ac.lk/mbl/microbe-but-not-microscopic/

2. ‌2.1: Sizes, Shapes, and Arrangements of Bacteria. (2016, March). Biology LibreTexts. https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Kaiser)/Unit_1%3A_Introduction_to_Microbiology_and_Prokaryotic_Cell_Anatomy/2%3A_The_Prokaryotic_Cell_-_Bacteria/2.1%3A_Sizes_Shapes_and_Arrangements_of_Bacteria

3. ‌Sushmita Baniya. (2022, July 22). Classification of Bacteria. Microbe Online; Microbe Online. https://microbeonline.com/classification-of-bacteria/

4. Epulopiscium fischelsoni. (2023). Mst.edu. https://web.mst.edu/~djwesten/MoW/BIO221_2009/E_fischelsoni.html

5. Microbiology Society. (2020). Bacteria | What is microbiology? Microbiologysociety.org. https://microbiologysociety.org/why-microbiology-matters/what-is microbiology/bacteria.html#:~:text=Bacteria%20are%20classified%20into%20five,in%20pairs%2C%20chains%20or%20clusters.

6. Nidhi Srivaths. (2022, February 16). Quorum Sensing: The Social Network of Bacteria - Research Blog. Research Blog. https://researchblog.duke.edu/2022/02/16/quorum-sensing-the-social-network-of-bacteria/

7. Christian. (2021, May 3). Análisis necesarios para clasificación de procariotas. Microbiología; Microbiología. https://microbiologia.net/microbiologia/analisis-para-clasificacion-procariotas/

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