How bacteria sacrifice themselves to render antibiotics ineffective
Filamentous cells resume cell division when CTX is removed. (A) E. coli REL606 was grown in a microfluidic flow chamber connected consecutively to two syringes, enabling the supply of nutrient medium with and w...
Bacteria can defend themselves against antibiotics with the help of an enzyme released by dying cells, according to a study by a team from the Institute for Biological Physics at the University of Cologne and Wageningen University & Research published in the Proceedings of the National Academy of Sciences. This discovery helps scientists understand bacterial survival mechanisms and improve the effectiveness of antibiotics.
The team, led by Dr. Joachim Krug in Cologne and Dr. Arjan de Visser in Wageningen, demonstrated that Escherichia coli (E. coli) bacteria can produce an enzyme that chemically breaks down the antibiotic, rendering it ineffective.
Because the enzyme is released particularly by dying bacteria, the researchers refer to this as "altruistic cell death," which ensures the survival of the population as a whole. These findings help explain bacteria's collective survival mechanisms, which, in turn, could contribute to improving the effectiveness of existing and future antibiotics.
The project was prompted by a discovery by the study's first author, Dr. Rotem Gross from the University of Cologne, who demonstrated that although bacterial cultures initially die off when exposed to the antibiotic, they eventually recover and continue to grow unhindered.
The team investigated two strains of E. coli bacteria—pathogens responsible for urinary tract infections, among other conditions, as well as septicemia and hospital-acquired infections—and their response to beta-lactams, the most widely used class of antibiotics worldwide. The bacteria produce the enzyme beta-lactamase, which chemically breaks down the antibiotic.
As soon as the antibiotic's concentration fell below a threshold level as a result of enzymatic activity, the bacterial cultures began to recover. "Therefore, the death of some of the bacteria contributes significantly to the long-term survival of the population as a whole, which can be interpreted as an example of altruistic collective behavior," Krug says.
In addition to the dying bacteria, the surviving bacteria also help fight off the antibiotic. They, too, produce the enzyme, but it remains inside the cell, where it degrades the absorbed antibiotic. The dying bacteria release the enzyme.
This occurs in both E. coli strains under investigation. However, the researchers noted that the extent to which cell death contributes to reducing the antibiotic varies considerably between the two E. coli strains studied. This suggests that the strains will also react differently to beta-lactamase inhibitors, as these are effective only in the culture medium and cannot penetrate intact cells.
Beta-lactamase inhibitors are substances designed to circumvent bacteria's resistance mechanisms. A higher level of altruistic cell death therefore makes the population more susceptible to these substances, which are already routinely used to treat infections.
"We were amazed by the variety of defense mechanisms that the bacteria are able to mobilize even under simple laboratory conditions," Krug says. This makes predicting the efficacy of specific antibiotics under realistic physiological conditions a major challenge, a task the team hopes to tackle in the future.
Publication details
Rotem Gross et al, Contributions of intra- and extracellular antibiotic degradation to collective β-lactam survival, Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2526410123
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Citation: How bacteria sacrifice themselves to render antibiotics ineffective (2026, July 16) retrieved 16 July 2026 from https://phys.org/news/2026-07-bacteria-sacrifice-antibiotics-ineffective.html
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