Bacterial classification may be more elusive than previously thought

June 19, 2017
Helicobacter pylori
Histopathology of Helicobacter pylori infection in a gastric foveolar pit demonstrated in endoscopic gastric biopsy. Credit: Wikipedia.

New research from Dartmouth College raises questions over how scientists should interpret observed groupings of bacteria. The study advises caution with the assumption that bacterial clusters are always a result of ecological and genetic forces.

The research, appearing in the Proceedings of the National Academy of Sciences, says random diversification and extinction of cells could organize bacteria into taxonomic units just as effectively as classification based on selection-driven ecological forces.

"A reliable classification system is the key to understanding ," said Olga Zhaxybayeva, assistant professor of biological sciences at Dartmouth College. "Through our research, we found that organizing microorganisms is even trickier than previously thought."

Scientists are currently divided over what factors to consider when classifying bacteria and other microorganisms. Some favor the so-called "periodic selection" model, in which the descendant of the most-fit genotype takes over the population and establishes a new group. Others advocate the "recombination" model, in which the frequent exchange of material between genes within causes organisms to cluster.

"Not knowing what is driving the organization of microorganisms makes the task of providing fast, accurate identification of difficult," said Zhaxybayeva. "Surprisingly, we found that a simple alternative may also explain grouping patterns, eliminating the need to invoke current models."

The research team, led by Zhaxybayeva, tested the idea that a simple birth-death cycle of cells can produce microbial clusters that look like groupings observed in nature. Analysis of hundreds of genomes within four bacterial groups - Escherichia spp., Borrelia spp., Neisseria spp. and Helicobacter pylori - produced patterns indistinguishable from those observed in most genes from three of the four bacterial groups.

As a result of the findings, the study recommends checking diversification of microbial groups against the proposed birth-death model before calling for more complex explanations.

Explore further: Gene transfer keeps bacteria fit

More information: Timothy J. Straub el al., "A null model for microbial diversification," PNAS (2017). www.pnas.org/cgi/doi/10.1073/pnas.1619993114

Related Stories

Gene transfer keeps bacteria fit

June 15, 2017

Researchers at the University of Basel's Biozentrum have discovered that Bartonella bacteria exchange genes efficiently using a domesticated virus encoded in their genome. As the findings published in Cell Systems demonstrate, ...

Dependency can be an evolutionary advantage

November 7, 2016

It has been known for quite some time that genetically modified bacteria, which have lost their ability to produce certain amino acids and retrieve these nutrients from their environment grow better than bacteria, which produce ...

Recommended for you

Scientists illuminate structures vital to virus replication

June 27, 2017

In the fight against the viruses that invade everyday life, seeing and understanding the battleground is essential. Scientists at the Morgridge Institute for Research have, for the first time, imaged molecular structures ...

What makes stem cells into perfect allrounders

June 27, 2017

Researchers from the University of Zurich and the University Hospital Zurich have discovered the protein that enables natural embryonic stem cells to form all body cells. In the case of embryonic stem cells maintained in ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.