The coordination and communication of brainless bacteria
Cooperation is a complicated process. Different parties need to understand each other’s goals well enough to adjust their behavior, even to the point of curbing their initial desires to find a compromise. With the number of variables in play, it’s even been suggested that cooperation is linked to more sophisticated brains, such as when a social lion might outperform a solitary leopard at cognitive tests. Or… it might be something that even ‘lowly’ fungi and bacteria can engage in, with absolutely no brain required.
Managing meal times
Bacteria colonies can grow into distinct populations, complete with an outer protective layer that seals in its members. These biofilms work together with the bacteria inside, but may end up competing with other bacterial biofilms for resources, even if they’re all the same species of bacteria. Rather than battle for every last speck of food in the petri dish, researchers found that Bacillus subtilis biofilms appear to coordinate their activity so that there’s enough food for both populations.
Within each biofilm, bacteria can communicate with each other, even using electrical signals that get passed between each cell. In aggregate, these signals can fall into a shared pattern of oscillating signals, and those signals have been observed to be linked to stimuli like the amount of food available at any given moment. When two biofilms meet up, their oscillations can be synced up, which results in everyone trying to eat the same resources at the same time. This was fine if there was a lot of food for each biofilm, but if food was harder to come by, they instead shifted to asynchronous oscillations. The bacteria basically adjusted their timing so that neither group was engaged in its “eat now” portion of activity at the same time, which meant they weren’t directly competing anymore. This generally resulted in better growth for both biofilms.
Sharing through smell
Electrical activity between similar cells isn’t the only form of microbial communication either. Serratia, a soil bacteria, has been observed trading information with Fusarium, a fungus that is pathogenic to plants. The two organisms weren’t exactly engaged in social banter with each other, but each was seen producing and reacting to chemicals known as terpenes. With no specific sensory organs for hearing or sight, the microbes were communicating with smells.
Further changes in behavior weren’t immediately tied to the terpene exchange, but it’s thought that smell is likely the most widely used medium for communication, with terpenes in particular being the lingua franca among most microorganisms.
Source: Distinct bacterial communities share nutrients for the common good, Scienmag
