Researchers at ISTA have discovered that E. coli bacteria under starvation stress use bacteriophages to shuffle genetic material, a process occurring 100 times more often than spontaneous mutations.

Scientists at the Institute of Science and Technology Austria (ISTA) have identified a process in Escherichia coli that mimics sexual reproduction. By utilizing CRISPR-Cas immune systems to interact with bacteriophages, bacteria can transfer and incorporate DNA into their own genomes. This mechanism, which occurs primarily under starvation conditions, allows bacterial populations to reshuffle genetic information and potentially accelerate their adaptation to changing environments.

The Role of Bacteriophages as Pollinators

While bacteriophages are typically lethal predators that destroy susceptible bacterial cells, the research team found they can act as 'pollinators' for immune bacteria. When bacteria possess CRISPR-Cas immunity, they can survive phage infection while the viruses inadvertently shuttle bacterial DNA between cells. This process allows recipient cells to integrate the transferred genetic material into their own genomes and pass it on to their offspring.

Adaptation Under Starvation Stress

The study indicates that this sex-like DNA exchange is linked to the bacteria's response to starvation. While bacteria typically reproduce asexually through binary fission under favorable conditions, the stress of limited resources triggers this alternative mechanism. By facilitating horizontal gene transfer, the bacteria can combine beneficial genetic variants more efficiently than relying on spontaneous mutations alone, which are often harmful or slow to arise.

Comparison to Existing Gene Transfer Mechanisms

This discovery builds upon known horizontal gene transfer methods, such as natural competence and conjugation, which were identified in the 20th century. Unlike these methods, which are limited by specific environmental requirements or direct cell-to-cell contact via a sex pilus, the phage-mediated process provides a distinct pathway for genetic variation. The researchers noted that this form of gene exchange occurs at a rate more than 100 times higher than that of spontaneous mutations.