Bacterial death factor discovered

A communication factor has been discovered that allows bacteria to coordinate their activities — and death — and could lead to the development of a new class of antibiotic medicines .

Although bacteria are traditionally considered unicellular organisms, increasing experimental evidence indicates that they seldom behave as isolated organisms.

Instead, they are members of a community in which the isolated organisms communicate among themselves, manifesting some multi-cellular behaviours.

In an article recently published in the journal Science, Prof Hanna Engelberg-Kulka and her team from the Hebrew University of Jerusalem describe the communication factor they discovered in the intestinal bacteria E. coli.

The factor is secreted by the E. coli and serves as a communication signal between single bacterial cells. It enables the activation of a built-in ‘suicide module’ located on the bacterial chromosome and is responsible for bacterial cell death under stressful conditions.

The new factor has since been labelled Extra-cellular Death Factor (EDF).

While suicidal cell death is counterproductive for the individual bacterial cell, EDF is activated under stressful conditions to kill off a sub-population within the bacterial culture, allowing the survival of the population as a whole.

Understanding how the EDF functions may provide a lead for a new and more efficient class of antibiotics, specifically aimed to trigger bacterial cell death in pathogens that carry the suicide module.

EDF is difficult to isolate, according to Prof Engelberg-Kulka. It is a peptide present in the bacterial culture only in minute amounts and it decomposes under conditions routinely used for standard chemical characterisation.

The research also identified several bacterial genes involved in the generation of EDF, she said.