A new research shows how bacteria come together in groups to form a collective memory so that their tolerance to stress is enhanced.
Individual bacterial cells are limited by a short memory. To counter this drawback, the bacteria develop collective memory in groups.
Bacteria require ‘stronger memory’ of a critical situation to be able to cope for a more critical one: they can thus survive exposure to a high concentration of salt better after they have been exposed to salt of a moderate concentration. However, individual cells do not enjoy such an advantage because the effect is only short-lasting.
On the other hand, when the bacteria are in groups, as opposed to being individually on their own, they develop a form of collective memory. A population having been exposed once to a ‘warning event’ will have greater survival rates when exposed a second time than one not having been exposed in advance.
How is this brought about? The cell cycles of the bacteria are synchronised due to the salt stress: cell division is delayed, allowing for the harmony to be established. Furthermore, the chance of surviving relies on the position of the individual bacterial cell in the cell cycle during the second exposure. Consequently, the population grows more tolerant to future stressful conditions, and the collective might also develop greater sensitivity than a population not having had a previous exposure.
Author Martin Ackermann explains that these findings will enable scientists to control bacterial cultures. For instance, they might be used to better understand the mechanisms employed by pathogens to develop resistance against antibiotics. Furthermore, the performance of bacteria used in industrial processes might be controlled.