Published on: January 28, 2025
The Secret Lives of Bacteria: Challenging Evolutionary Myths
A recent study led by Kostas Konstantinidis from the Georgia Institute of Technology is reshaping our understanding of bacterial evolution. This research challenges long-held assumptions about how bacteria form and maintain species. While traditional evolutionary theories have struggled to explain the cohesion of bacterial species, this new study offers an intriguing perspective that raises questions about the adequacy of these theories.
DNA Exchange and Species Cohesion
The study reveals that bacteria frequently exchange DNA within their species, a process known as homologous recombination. This genetic exchange plays a crucial role in maintaining the boundaries between different bacterial species.
For decades, scientists believed that bacteria could not form distinct species due to their unique mechanisms of genetic exchange and their vast global populations. However, this groundbreaking discovery suggests that bacteria are capable of forming and maintaining species boundaries through frequent DNA exchanges.
“Understanding how individual microbes within the same species maintain their cohesiveness has been a significant question,” said Konstantinidis, the Richard C. Tucker Professor in Georgia Tech’s School of Civil and Environmental Engineering. “In other words, how do bacteria stay similar?”
Research Methods and Findings
Konstantinidis and his team analyzed the complete genomes of over 100 strains of Salinibacter ruber, a salt-loving microbe, collected from solar salterns in Spain. They also examined previously published Escherichia coli genomes isolated from livestock farms in the UK. By comparing the genomes of closely related microbes, they discovered that homologous recombination occurs frequently and randomly across the entire genome, not just in specific regions.
Their findings indicate that this constant exchange of genetic material acts as a cohesive force, keeping members of the same species similar. Moreover, they observed that members of the same species are more likely to exchange DNA with each other than with members of different species, further contributing to distinct species boundaries.
Implications for Science and Beyond
This research has profound implications for various fields, including environmental science, medicine, and public health. It provides valuable insights into identifying, modeling, and regulating clinically or environmentally important organisms. Additionally, the methodology developed during the research offers a molecular toolkit for future epidemiological and micro-diversity studies.
“The next question for us was how individual microbes in the same species maintain their cohesiveness. In other words, how do bacteria stay similar?” said Konstantinidis. The answer lies in the intricate processes that enable bacteria to maintain their species identity, challenging the notion that random mutations and natural selection alone can account for such complex behaviors.
References
- Paper: Roth E. Conrad, Catherine E. Brink, Tomeu Viver, Luis M. Rodriguez-R, Borja Aldeguer-Riquelme, Janet K. Hatt, Stephanus N. Venter, Ramon Rossello-Mora, Rudolf Amann, and Konstantinos T. Konstantinidis. “Microbial species and intraspecies units exist and are maintained by ecological cohesiveness coupled to high homologous recombination”. Nature Communications, November 15, 2024.
- DOI: 10.1038/s41467-024-53787-0
- Funding: U.S. Department of Energy, U.S. National Science Foundation, European Regional Development Fund
This research underscores the complexity of microbial life and highlights the limitations of current evolutionary models in explaining the cohesion and diversity of bacterial species. It prompts us to reconsider the fundamental mechanisms driving the formation and maintenance of species, inviting further exploration into the intricacies of life at the microscopic level.