Electrical and chemical communication among microbes has been an active area of research for a while, but this new study looks at how B. subtilis communicates not just among individuals, but between distinct biofilms. They demonstrate that resource limitation prompts an anti-phase growth pattern synchronization - the suggestion being that time with full resource availability is better than the same amount of time with half of that resource. That seems logical enough, but why the growth phase periods are the same between the two cases (suggesting that fewer nutrients overall are being consumed), and why anti-phase relationships aren't also favored under nutrient-replete conditions, is unclear. Perhaps most surprisingly, the researchers show that under limitation, the average growth rate is actually higher in two anti-phase biofilms than one big biofilm! Lots of outstanding questions, but this is a great place to start with community-level biochemical communication.
Link [here], abstract below:
Bacteria within communities can interact to organize their behavior. It remains unclear whether such interactions extend beyond a single community to coordinate the behavior of distant populations. We discovered that two Bacillus subtilis biofilm communities undergoing metabolic oscillations become coupled through electrical signaling and synchronize their growth dynamics. Coupling increases competition by also synchronizing demand for limited nutrients. As predicted by mathematical modeling, we confirm that biofilms resolve this conflict by switching from in-phase to anti-phase oscillations. This results in time-sharing behavior where each community takes turns consuming nutrients. Time-sharing enables biofilms to counterintuitively increase growth under reduced nutrient supply. Distant biofilms can thus coordinate their behavior to resolve nutrient competition through time-sharing, a strategy used in engineered systems to allocate limited resources.