Researchers have found that bacteria can detect potential threats earlier than expected by utilizing a broad danger signal. They are able to sense the death of nearby cells and proactively create a defensive biofilm. Gaining insight into how bacteria communicate and react to dangers is essential for addressing infections.
Researchers at the University of Basel have found that bacteria have the capability to sense potential threats ahead of time through a general danger signal. They can recognize when neighboring cells are dying and actively construct a protective biofilm. Learning about how bacteria interact and respond to risks is vital for fighting infections.
Bacteria are in a continual battle for survival against threats such as immune cells, antibiotics, and phages—viruses that specifically infect bacteria. Through evolution, these microorganisms have devised many methods to shield themselves from such risks. So, how exactly do bacteria detect possible dangers in their surroundings and take protective action?
Danger signal: Cell wall fragments
In a recent study led by Prof. Knut Drescher at the Biozentrum of the University of Basel, it was revealed that fragments of the bacterial cell wall, known as peptidoglycans, act as a distress signal indicating potential danger in the environment.
“These molecules serve as an all-encompassing danger signal that is recognized not only by similar bacterial species but also by different species altogether,” Drescher explains. “Peptidoglycans are released when bacteria are destroyed by phages or antibiotics.”
Protective mechanism: Biofilm formation
In response to this danger signal, bacteria produce a small signaling molecule called c-di-GMP, which initiates the process of biofilm formation. Biofilms consist of intricate, three-dimensional communities of living bacteria encased in a slimy matrix. “In Vibrio cholerae, the bacteria responsible for cholera, just a short exposure to cell wall fragments can trigger biofilm formation,” notes Sanika Vaidya, the lead author of the study. Within these biofilms, bacteria are shielded from attacks by phages, immune cells, and antibiotics.
Survival strategy: Cross-species warning
The researchers noted this behavior not only in cholera-causing bacteria but also in other dangerous and often multi-drug resistant pathogens such as Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, and Enterococcus faecalis.
The observation that bacteria from different species respond similarly to the same danger signal implies a universal survival tactic. “Interestingly, human immune cells also detect peptidoglycan fragments as a sign of infection,” Drescher points out. “This reveals surprising similarities between the defense mechanisms of bacteria and humans.”
Clinical relevance: Preventing biofilms
This universal strategy for survival may help explain the significant role biofilms play in various settings—from natural ecosystems to human infections. However, the study presents new questions: Do cell wall fragments trigger other protective responses apart from biofilm formation? And how can these new findings be utilized to combat pathogens that form biofilms more effectively?
