This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: How do bacteria adapt when resources run low? ISTA researchers have found that, under starvation stress, E. coli can use bacteriophages and CRISPR-Cas immunity to transfer and incorporate DNA, accelerating genetic reshuffling.
The process resembles a primitive form of sexual reproduction and may help bacterial populations adapt to changing conditions. The findings were published in Molecular Biology and Evolution. For decades, scientists thought that bacteria reproduced by asexual cell division, known as binary fission, and occasionally took up free DNA or exchanged genetic material "horizontally" from cell to cell.
However, evidence suggesting a primitive form of sexual reproduction started to emerge in the 1990s. But how common is this phenomenon? Now, Pavel Payne and Călin Guet, a postdoc and a professor at the Institute of Science and Technology Austria (ISTA), have uncovered a process resembling sexual reproduction in the gut bacteria Escherichia coli.
"The twist is that the bacteria make use of CRISPR-Cas, a defense system against bacterial viruses that later became the basis for gene-editing technologies," says Guet. "It turns out that bacteria use these viruses to shuttle DNA between themselves. Furthermore, recipient cells can incorporate this DNA into their own genomes and transmit it vertically to their offspring, which is de facto sex." This DNA transfer process appears to occur when bacteria are close to starvation.
The work builds on the discovery of horizontal gene transfer (HGT)—the movement of genetic material between organisms by mechanisms other than vertical inheritance, from parent cell to daughter cell. This phenomenon was described almost 100 years ago when so-called natural competence was discovered in bacteria. This mechanism is a genetically encoded state that allows bacteria to actively take up free DNA in their environment and integrate it into their genomes.
However, far from being a widespread process, only a small minority of bacteria are naturally capable of doing so. In the 1940s, another form of HGT called "conjugation" was discovered. It enables bacteria to transfer genetic material, including antibiotic-resistance genes, through cell-to-cell contact using a tubelike structure called a sex pilus.
Extract — continue reading at the source.
