Even though they’re genetically identical and live in the same environment, not all bacteria are the same. When times are tough more bacteria become individualists gobbling resources in the detriment of the colony, but in doing so the individualists actually enhance the colony’s survival rate.

Any living being, bacterial or complex like a human, needs to be capable of sensing solutions to two problems: what resources are available right now to ensure survival and replication, and how will this resource availability change in time. If you sense that resources are dwindling over time, the organism must prepare for dark times ahead.

Researchers from Eawag, ETH Zurich, EPFL Lausanne, and the Max Planck Institute for Marine Microbiology in Bremen proved that bacteria are perfectly capable of doing just this, although the general view is that they essentially behave as a collective, and less like an individual.

The team painstakingly studied individual bacteria from bacterial colonies to see how they respond to the lack of nutrients. The Klebsiella oxytoca bacteria likes to feed on nitrogen from ammonia, but when there’s no enough ammonia some go about the more energy intensive route of fixing it from elementary nitrogen, the researchers found. This sort of behaviour might seem like against the greater good of the colony because other bacteria will starve. In the long run, however, when the ammonia finally runs out, at least some individuals are prepared.

Single cells of the bacterium Klebsiella oxytoca. The color differences between individual cells show that genetically identical cells within a population incorporate differing amounts of nitrogen into their cell mass (warmer colors represent more nitrogen incorporation). Credit: F. Schreiber

This is striking because “although all of the bacteria in the group are genetically identical and exposed to the same environmental conditions, the individual cells differ among themselves,” says Frank Schreiber, one of the study’s co-author.

This sort of insight wouldn’t have been possible if the scientists involved hadn’t thought outside the box. Typically, biologists study the collective properties of bacterial colonies made of millions or billions of bacteria.

“The results indicate that phenotypic heterogeneity is a general solution to two important ecological challenges—nutrient limitation and fluctuations—that many microorganisms face,” the study’s abstract reads.

The big takeaway is that biological diversity does not only matter in terms of genetics but also individual action.