For a long time, scientists thought bacteria didn’t form species like plants and animals do.
This was because bacteria reproduce asexually, by splitting into two, and can swap bits of genetic material with any other bacteria they come across.
It seemed impossible for bacteria to organize into distinct groups or species.
But groundbreaking work by Professor Kostas Konstantinidis of Georgia Tech has shown that bacteria do form species, and a new study reveals something even more surprising: bacteria have a way of staying genetically cohesive that’s a bit like having “sex.”
The study, published in the journal Nature Communications, investigated how bacteria maintain their distinct species despite their asexual reproduction.
“The big question for us was how bacteria stay similar to others in their species,” Konstantinidis explained.
Using new methods to analyze genetic material, the research team looked at two natural bacterial populations. They studied over 100 strains of Salinibacter ruber, a salt-loving microbe found in Spanish salt ponds, and a collection of Escherichia coli (E. coli) genomes from farms in the U.K.
The team discovered that bacteria frequently exchange DNA through a process called “homologous recombination.” In this process, bacteria trade pieces of DNA with each other. The new DNA gets integrated into their genomes, replacing similar pieces of their original DNA. This swapping doesn’t happen in just one part of the genome but spreads randomly across it.
While this DNA swapping isn’t exactly the same as sexual reproduction in animals or plants, it has a similar effect. It helps keep members of the same bacterial species genetically similar. Konstantinidis described this constant genetic exchange as a “glue” that holds bacterial species together.
One of the most important findings was that bacteria prefer to exchange DNA with members of their own species rather than with bacteria from other species. This preference strengthens the boundaries between species, ensuring they remain distinct.
“This work solves a long-standing puzzle in microbiology,” said Konstantinidis. “We now have a better idea of how to define bacterial species and understand the mechanisms that keep them cohesive.”
This research could impact many areas, from understanding how bacteria evolve in nature to finding better ways to fight harmful bacteria in medicine. For example, knowing how bacteria form and maintain species could help scientists track disease outbreaks or study how bacteria adapt to changing environments.
The team’s new methods also offer tools for future studies in microbiology, such as exploring genetic diversity or tackling antibiotic resistance.
In short, while bacteria may not have “sex lives” in the way humans do, their frequent DNA exchanges play a crucial role in keeping their species distinct and thriving. This discovery opens up exciting new directions for studying life’s tiniest organisms.
Source: Georgia Institute of Technology.
