Bacteria With Memories?

Most people know that bacteria grow pretty fast. But what if I told you that one factor for this growth is the ‘memory’ of collective bacteria?

Let’s break this down. This isn’t necessarily the actual memory of individual bacterial strains; rather, it is the memory built on environmental conditions created by former and current bacteria within the microbial growth community. Thus, the storing of bacterial ‘memories’ takes place within the environment as a legacy effect, not inside the cells themselves.

This property of bacteria can be seen as a prominent feature of molecular biology. To make conceptual understanding easier, let’s look at yogurt as an example. Yogurt is made when Lactobacillus bulgaricus and Streptococcus thermophilus species of bacteria convert the lactose into lactic acid. After leaving the yogurt to sit for a few hours in warm temperatures to facilitate bacterial reactions, the concentrated acidity of the milk inside will rise. This change in environmental acidity causes the yogurt to thicken and develop its unique taste (The Nutrition Source).

Inside the yogurt, bacterial communities develop collective memory from the environment created by their previous generations. To add clarification, the collective memory of bacteria is caused by “… .past growth conditions—in this case, temperature and oxygen. . . [which] can lead to different environmental changes by the bacteria and, thus, different future interaction outcomes” (Gajrani, Ye, and Ratzke). Thus, fermentation is the optimal experiment where we can grow bacterial communities that build on themselves over time. So, what does collective bacterial memory have to do with anything?

Simply put, collective bacterial memory can be either a positive or a negative property, depending on the context. If you were unfortunate enough to have an open wound from a physical injury, prior bacterial communities can develop environments that facilitate the flourishing of certain strains of bacteria, which can lead to more bacteria– some of which may already have antibacterial resistance, possibly making medical treatment much harder. On the other hand, you could be enjoying yogurt cultivated from bacterial communities that produce lactic acid, tasting the rich flavors of the world of dairy.

To summarize, bacteria can develop collective memory from their surrounding environment, which may be created by previous generations of bacterial communities. I hope you learned something new in this article!  

Work Cited:

“Yogurt &Bull; the Nutrition Source.” The Nutrition Source – Harvard Chan School, Nov. 2019, nutritionsource.hsph.harvard.edu/food-features/yogurt. Accessed 18 Nov. 2025.