ATL Standard

Kostas Konstantinidis, a researcher at Georgia Tech, has published new findings challenging the long-held belief that bacteria cannot form distinct species. His previous work demonstrated that microbes, like plants and animals, are organized into species. This recent study suggests that bacteria not only form species but maintain them through a process akin to sexual reproduction.

Konstantinidis explained the focus of their research: “The next question for us was how individual microbes in the same species maintain their cohesiveness. In other words, how do bacteria stay similar?” He is a professor in Georgia Tech’s School of Civil and Environmental Engineering.

Traditionally, bacterial evolution is thought to occur mainly through binary fission—a form of asexual reproduction—with occasional genetic exchanges. However, using innovative bioinformatic methods and comprehensive genome data, Konstantinidis and his international team discovered that bacteria evolve more "sexually" than previously believed.

Their study involved analyzing complete genomes from two microbial populations: Salinibacter ruber from Spain's solar salterns and Escherichia coli from U.K. livestock farms. They compared these genomes to observe gene exchange patterns.

The researchers identified homologous recombination as a significant factor in maintaining microbial species integrity. This process involves DNA exchange between microbes, integrating new DNA by replacing similar sequences within their genome. Unlike sexual reproduction in higher organisms where DNA exchange occurs during meiosis, this recombination happens frequently across entire microbial genomes.

Konstantinidis noted: “This may be fundamentally different from sexual reproduction in animals, plants, fungi, and non-bacterial organisms...but the outcome in terms of species cohesion may be similar.” The frequent genetic material exchange acts as a cohesive force among members of the same species.

Moreover, they found that microbes tend to exchange DNA more with their own species than with others, reinforcing distinct boundaries between species.

“This work addresses a major, long-lasting problem for microbiology...how to define species and the underlying mechanisms for species cohesion,” said Konstantinidis.

This research impacts various fields such as environmental science, evolution, medicine, and public health by providing insights into identifying and regulating important organisms. It also offers a molecular toolkit for future epidemiological studies.

The study was supported by contributions from Ramon Rossello-Mora's group at IMEDEA in Spain and Rudolf Amann's group at the Max Planck Institute for Marine Microbiology in Germany. These groups helped gather data from natural microbial populations and contributed to data analysis.

The findings were published in Nature Communications under DOI: https://doi.org/10.1038/s41467-024-53787-0. Funding came from several sources including the U.S. Department of Energy and the European Regional Development Fund.