When I embarked upon my career in the fermentation industry, I was surprised by the complexity surrounding taxonomy or more simply put, the scientific names of microorganisms. In the same way as human history, the taxonomy of microorganisms is not linear. The only constant is change.
Thanks to scientific discoveries and the evolution of biotechnology, researchers are regularly reclassifying and renaming bacteria, yeasts, and other microorganisms. This impacts my work, and probably yours, for different reasons.
In this blog, I will paint a quick picture of the taxonomy of microorganisms and why it evolves.
How microorganisms are named by the scientific community?
Taxonomy is a discipline in biology. It aims at describing living organisms and regrouping them in order to identify, name and classify them.
Each microorganism has a unique, specific name. This nomenclature is overseen by committees and with different rules according to the microorganisms :
- Virus: International Code of Virus Classification and Nomenclature
- Bacteria and archaea: International Committee on Systematics of Prokaryotes, ICSP (previously, International Committee on Systematics of Bacteriology)
- Fungi, algae and plantes: International Code of Nomenclature for algae, fungi and plants (not-for-profit organisation)
These organisations are collaborating with the scientific community to create a standardized nomenclature. Scientists can make proposals for a new taxonomy based on evidence from their research.
The scientific name of microorganisms is written in Latin. It is made up of two parts: genus and species.
Let’s take baker’s yeast as an example:
Saccharomyces [genus] cerevisiae [species]
Classification can go as far as strain or variant so as to differentiate between microorganisms who show different variations of observable behaviour (called ‘phenotype’ in scientific language).
Staying with our baker’s yeast:
Saccharomyces [genus] cerevisiae [species] var cerevisiae [strain]
But another strain of S. cerevisiae could be:
Saccharomyces [genus] cerevisiae [species] var boulardii [strain]
The two strains are nearly identical at a molecular level but Saccharomyces cerevisiae boulardii shows more physiological resistance to heat and acidic stress. Saccharomyces boulardii and Saccharomyces cerevisiae are two closely related strains used either as a probiotic or in the preparation of food and wine.
Why is the taxonomy of microorganisms evolving over time?
The naming of microorganisms evolves and is closely linked to scientific progress, notably genetic analysis methods. The graph below, created by EzBioCloud, shows the correlation between the genetic sequencing of bacteria and archaea and the number of new species in scientific journals. Among these new species, some already existed under other names.
EzBioCloud publishes a dashboard showing the genetic diversity and taxonomy of bacteria and archaea. It is quite complete and regularly updated.
Without going into too much detail of the genetic techniques, here are some of the other factors that can lead to the reclassification of microorganisms:
- Taxonomy: a global review of the rules pertaining to taxonomy can be the origin of important changes (1) (2).
- Behaviour: by exposing microorganisms to new environments, scientists can discover previously unknown variations in phenotype.
- Structure: the observable morphology of microorganisms has an impact on their classification. This factor can vary, depending on the stage of microorganism development throughout their study by scientists.
- Interaction with humans: when a microorganism comes into contact with us, it can show different behaviour not always observed beforehand.
This list is not exhaustive but shows just how far taxonomy is a living, evolving field of research. It is important to know when and how to check this taxonomy. Indeed, this information can influence the success or failure of your research and development projects.
In our next blog, you will get to know why you should care about the scientific names of microorganisms and how to check them out.
(1) “An Update on the Novel Genera and Species and Revised Taxonomic Status of Bacterial Organisms Described in 2016 and 2017”; Erik Munson, Karen C. Carroll; Journal of Clinical Microbiology Jan 2019, 57, 2: e01181-18; DOI: 10.1128/JCM.01181-18
(2) “A history of research on yeasts 8: taxonomy”; James A. Barnett; Yeast 2004; 21: 1141–1193; DOI: 10.1002/yea.1154