When taxonomic revisions shift research foci

Taxonomic nomenclature, i.e., the naming and classification of life, is expected to be a very important facet of biological research, given it governs how we differentiate between different organisms and can even refer to them. Thus, it is also expected that reclassifications, particularly of clinically or commercially relevant organisms, can be of significant interest not only to researchers but also in healthcare, governmental regulations, and more. It can even significantly affect businesses' finances, not only in terms of updating packaging with revised names but also marketing and more to communicate the change to customers.

So, in 2020, when this seminal paper revising the taxonomy of lactic acid bacteria (LAB) of the family Lactobacillaceae was published in the International Journal of Systematic and Evolutionary Microbiology, it caused a major uproar as biologists, clinicians, businesses, and government agencies all had something to say.

What about shifts in research interest? Did research interest shift permanently away from certain taxa, but towards others?

If you are interested in the full analysis, it was performed in Kaggle and can be found here.

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LABs are a common component of probiotic products, and therein lies the issue. First, research interest can be at a genus level, or in other words, 'related groups' of species. However, when taxonomic classification does not match phylogeny, which is the study of how related organisms are, there can be confusion as to what characteristics of certain groups are and what are not. Imagine if distinct organisms with distinct features are grouped together as the same 'creature,' then it would seem rather strange that they comprise such disparate characteristics. Here, the re-classification of LABs did split many of the older groups into multiple ones that better align with the distinct characteristics, seeming to cause interest to firstly be raised regarding novel groups that have been understudied and secondly, to return to those that previously had research interest drawn away due to the confusions that had arisen.

All in all, the revision resulted in the re-classification of LABs from the family Lactobacillaceae into 25 genera (plural of 'genus'), up from two. In other words, there were 23 whole new genera to which many of the species were re-classified.

To evaluate the research interest in the research interest in these genera, I evaluated a proxy, the number of peer-reviewed articles that include a genus name in some form - whether a tag, citation, or just mentioned somewhere in the text.

I evaluated the 20 years from 2005 to 2024 inclusive and determined the number of counts per year. Some cleaning was required to entirely irrelevant publications, such as where an author shared their name with a genus versus actually being mentioned. I then normalized the data so that it is easier to visualize. The results of publication counts are as follows.

Lactobacillus and Paralactobacillus are the two genera that existed before 2020, and research interest in them significantly dropped after 2020, in fact, by more than 30% between 2022 and 2023 alone. However, while research interest in Paralactobacillus continued to decline, Lactobacillus rose again in 2024 and is likely to return to its former glory.

Research interest in the novel genera increased initially but mostly did not see exponential growth and even declined by 2023.

Clearly, such major revisions impacted research interest significantly in the short term. Still, for well-studied microorganisms such as Lactobacillus, even if some of those previously classified to this genus were then re-classified to a different genus, research interest ultimately persisted.

Through all this, there was one standout novel genus that received ever-increasing research interest -  Lactiplantibacillus, which is associated with both fermented food products as well as plant matter. Interestingly, research interest in members of this genus was not significant before 2020, even when they were still classified as Lactobacillus. This is a particular case where the taxonomic revisions clearly significantly drove new research interest, likely highlighting these microorganisms as new targets of interest thanks to the re-classification.

So there you go. If you work in biotechnology, specifically fermentation, Lactiplantibacillus is probably the LAB to investigate among the Lactobacillaceae.