Most people are rather familiar with the idea of an internal body clock. We get tired at night, we are more awake during the day, and disruptions to our sleep schedules leave us feeling miserable for the entire day. That’s how our circadian rhythms work. It is easy to think of it as a very human thing, but a lot of living organisms have some version of this clock. Including surprisingly small ones!
Take cyanobacteria, for example. They are tiny microorganisms that use sunlight to make energy, just like plants do. They are often described as simple, but they are capable of some rather complex things. For instance, they don’t just respond to light when it appears, instead they can anticipate it due to their own internal timing system. Something else that’s fascinating about cyanobacteria is that they can produce electricity. This process is called exoelectrogenesis, and it means that these bacteria can move electrons outside of their cells and generate a small electric current. Not a huge amount of energy or anything, but it is still a useful surprise that living cells can do this at all. This ability is attracting interest because it could potentially be used in bioelectronic devices and bioenergy systems.
One question that I’ve been thinking about in my research is whether these two phenomena are connected. If cyanobacteria have a circadian rhythm, and they can also produce electricity, does their timing system affect when or how much electricity they produce? And is there a point in the day when they are “better” at it?
To this, I don’t have a complete answer yet, but the idea is that their internal clock might regulate processes involved in electron transfer, the movement of electrons that ultimately generates an electric current. Since a lot of their activity is already linked to light and dark cycles, it would not be overly surprising if electricity production also followed some kind of daily pattern. But actually showing that and understanding how it works is much more complicated.
I believe one important matter of this research is its potential application in fields like bioenergy. If bacteria are going to be used in systems that generate electricity, it would be useful to know if their output changes over time in a predictable way. And if it does, then maybe those systems could be designed to work together with these rhythms. That is a far-into-the-future idea, though.
There are still many unanswered questions. The exact mechanisms behind exoelectrogenesis in cyanobacteria aren’t fully understood, and adding circadian regulation into the mix makes it even more complex. So, at this stage, it is more about exploring the relationship and seeing if there is a pattern.
It is strange to think that something so small can keep time and produce electricity at the same time... but maybe that’s what makes cyanobacteria so fascinating? The more we look, the less “simple” the tiny things really are.
Arina K. Ytterstad
The author is a PhD researcher at the Department of Life Technologies, where they study cyanobacterial exoelectrogenesis and circadian regulation. Their research explores how biological timing systems influence microbial electricity production.
Sources:
1. Wey, L. T., Bos, P. R., Crosbie, M., Ortega Martínez, P., Tiwari, A., & Nikkanen, L. (2026). Electron Transport Reactions of Cyanobacterial Photosynthesis and state-of-the-art in vivo measurement techniques. Plant Physiology, kiag107. https://doi.org/10.1093/plphys/kiag107
2. Wey, L. T., Lawrence, J. M., Chen, X., Clark, R., Lea-Smith, D. J., Zhang, J. Z., & Howe, C. J. (2021). A biophotoelectrochemical approach to unravelling the role of cyanobacterial cell structures in exoelectrogenesis. Electrochimica Acta, 395, 139214. https://doi.org/10.1016/j.electacta.2021.139214
3. Wey, L. T., Bombelli, P., Chen, X., Lawrence, J. M., Rabideau, C. M., Rowden, S. J. L., Zhang, J. Z., & Howe, C. J. (2019). The development of biophotovoltaic systems for power generation and biological analysis. ChemElectroChem, 6(21), 5375–5386. https://doi.org/10.1002/celc.201900997
4. Cohen, S. E., & Golden, S. S. (2015). Circadian rhythms in cyanobacteria. Microbiology and Molecular Biology Reviews, 79(4), 373–385. https://doi.org/10.1128/MMBR.00036-15
