Scientists have discovered that bacteria can communicate viral threats in order to respond with a cooperative defense. Bacteria can “sense” the size of the bacterial colony to estimate the chance of viral exposure. The details are in a paper that was just published in the journal Molecular Cell.
Large bacterial colonies are always at risk of being infected by deadly viruses. A virus can quickly wipe out an entire colony if the bacteria aren’t ready to adapt and defend. Although living in high population densities allows bacteria to easily share resources and genes, it also makes them more vulnerable to dangerous infections. Scientists already know that bacteria can communicate through a process called quorum sensing (QS) signaling. It was unclear if this form of communication was also used in the immune system response, however.
Researchers from the Department of Microbiology and Immunology at the University of Otago in New Zealand studied Serratia bacterial cells. They first exposed the bacterial colonies to viruses. Bacteria are normally quick to develop resistances to the types of viruses used in the study. When QS signaling was inhibited in a colony, that colony was slower to react to the viral threat. These same colonies struggled to coordinate and were more vulnerable to infection. The colonies that could communicate with QS were quicker to acquire immunity to the virus. This shows that bacterial communication is critical in helping the entire colony survive a viral outbreak. Chemical communication, including QS, allows bacteria to cooperate in order to fend off a viral threat.
The team’s findings provide new insights into how bacterial colonies protect themselves and respond to viral threats. Communication and coordination are key; bacteria use QS signaling to cooperate. By understanding bacterial immune responses, scientists can develop better medical treatments. The data can also help researchers predict how a bacterial colony will respond to specific dangers.
Patterson et al. Quorum Sensing Controls Adaptive Immunity through the Regulation of Multiple CRISPR-Cas Systems. Molecular Cell (2016).