Scientists discover DNA robbery of bacteria

How bacteria kill competitors to get their resistance

Predatory bacteria - sounds like a dark sci-fi scenario, but a study by the Biozentrum at the University of Basel documented that this behavior is real in bacteria. The research team led by Professor Marek Basler shows in the study that bacteria not only develop antibiotic resistance themselves, but also steal it from other bacteria with the help of poison. The results were published in the magazine "Cell Reports".

The researchers were able to document how some bacteria injected their competitors with a poison cocktail, causing them to burst. The attackers then took up the available genetic material. Thus, bacteria can collect resistance without having trained themselves, the University of Basel in a press release. The winner of the bacterial attack could then multiply undisturbed. This mechanism is particularly problematic in hospitals, where numerous germs are used and various antibiotics are used, against which more frequent resistance develops.

Multi-drug resistant bacteria can become a deadly hazard

If such multidrug-resistant bacteria multiply undisturbed, they can be a deadly danger for patients, since no more antibiotic acts. According to the researchers at the University of Basel, this development is sometimes the result of frequent and often careless use of antibiotics. The unnecessary use of antibiotics contributes to increasing the spread of resistance.

The Iraq germ as an example of multi-resistance

The bacterium Acinetobacter baumannii is a typical hospital germ. In the Iraq war, multidrug-resistant bacteria of this type caused difficult-to-treat wound infections in American soldiers. Therefore, this bacterium is colloquially referred to as "Iraq germ". The model organism of the study was Acinetobacter baylyi, a close relative of the Iraqi germ. Professor Marek Basler's team identified in the study five poison proteins, so-called effectors, which act differently. "Some of these toxic proteins kill the enemy very effectively, but they do not destroy the cell," explains Basler. Other toxic proteins would only damage the cell envelope so badly that the attacked bacterium breaks down and emits genetic material.

What happens after the poisoning??

According to the study, the aggressor incurs DNA fragments released after a successful attack. If there are genes on the fragments that are responsible for a particular resistance, the new owner will also become resistant. As a result, an antibiotic against which resistance has developed is no longer effective and the germ can multiply largely undisturbed.

Multiresistenzen also with infectious agents

"A set of different effectors can also be found in other infectious agents such as the causative agent of pneumonia or the cholera pathogen," says Basler. However, not all poisonous proteins would work equally well, as many bacteria have developed or acquired antidotes, so-called immunity proteins. The immunoproteins of the five effectors documented in the study could also be identified. For the attackers, it makes sense to produce not just a single poison protein, but a cocktail of different toxins with different modes of action. "This increases the likelihood that the opponent can be eliminated successfully and in some cases, by the dissolution of the cell, also its DNA becomes available," explains Basler. (Fp)