A groundbreaking discovery has challenged a long-held belief in the scientific community, revealing that bacteria, like plants and animals, are organized into distinct species. This research, led by Kostas Konstantinidis, the Richard C. Tucker Professor in Georgia Tech's School of Civil and Environmental Engineering, has overturned the traditional view that bacteria, due to their unique genetic exchange mechanisms and vast global populations, could not form distinct species.
Konstantinidis and his collaborators have further demonstrated that bacteria not only form species but also maintain their cohesiveness through a process akin to "sexual" reproduction. This finding challenges the prevailing understanding of bacterial evolution, which has long been considered primarily asexual.
The research team, using a novel bioinformatic method for detecting gene transfer and a comprehensive dataset of whole genomes, investigated how microbial species maintain their distinct identities. They analyzed the complete genomes of microbes from two natural populations: Salinibacter ruber, a salt-loving microbe, and Escherichia coli, a common bacterium found in livestock.
Their analysis revealed that "homologous recombination" plays a crucial role in maintaining microbial species cohesion. This process involves microbes exchanging DNA with each other and integrating the new DNA into their genome, replacing similar DNA segments. The researchers observed that recombination occurs frequently and randomly across the entire genome, not just in specific regions.
This finding suggests that bacteria evolve and form species in a more "sexual" manner than previously thought. While the process may differ from sexual reproduction in animals, plants, and fungi, the outcome in terms of species cohesion is similar. The constant exchange of genetic material acts as a cohesive force, keeping members of the same species similar.
The researchers also discovered that members of the same species are more likely to exchange DNA with each other than with members of different species, further reinforcing the distinct boundaries between species. This research has significant implications for various fields, including environmental science, evolution, medicine, and public health, providing valuable insights for identifying, modeling, and regulating clinically or environmentally important organisms.