Bacteria Can Tell Time: A Revolutionary Discovery in Circadian Rhythms

Recent study reveals that bacteria, specifically cyanobacteria, can indeed “tell time” by using internal 24-hour circadian clocks to anticipate environmental changes, especially seasonal shifts. This discovery, supported by an “ice bucket challenge” experiment, holds major implications for understanding how circadian rhythms affect the ability of organisms to adapt to environmental stressors such as climate change.

Bacteria's Internal Clocks: A Mechanism for Anticipation

The study/research headed by Dr. Luísa Jabbur, in partnership with the Johnson lab at Vanderbilt University, concentrated on how cyanobacteria adjust their physiology in response to varying day lengths. The researchers subjected cyanobacteria to artificial day lengths- short days, equinox days, and long days- under warm temperatures, followed by a cold shock through an ice bucket challenge. The survival rates of the bacteria showed that those exposed to many consecutive short days had majorly higher resistance to cold temperatures, with survival rates reaching up to 75%, three times bigger than those with longer day exposure. As Dr. Jabbur explains, the bacteria “use their internal clocks to measure day length” and switch their physiological state in preparation for winter. This anticipatory mechanism, called photoperiodism, allows the bacteria to adjust their metabolism and cold resistance before the arrival of winter. Interestingly, when the researchers removed the genes responsible for the bacteria's biological clocks, the survival rates were unaffected by day length, proving that these internal clocks are crucial for adaptation to environmental changes.

Implications for Broader Scientific Research

This finding is groundbreaking because it indicates for the first time that bacteria utilize photoperiodism to prepare for seasonal cues. Previously, this mechanism was thought to exist only in higher organisms like animals and plants, but this research shows that bacteria possess similar capabilities. “It is like they are signaling to their daughter cells and their granddaughter cells, passing information that the days are getting short, you need to do something,” Jabbur adds, highlighting how the bacteria’s internal clocks can be passed across generations, despite their short lifespan of six to 24 hours. The research opens new avenues for exploring how circadian rhythms and photoperiodism evolved in simple organisms and how these systems could help species survive in rapidly changing climates. Dr. Jabbur and her colleagues are keen to further investigate how cyanobacteria, as a fast-reproducing model, may offer insights into photo-periodic responses in other species. This work could have significant implications for agricultural crops, especially in knowing how plants may adapt to climate changes.

Also, Jabbur’s study brings attention to the potential molecular memory system within bacteria, which allows information from one generation to the next to influence their physiological responses to environmental changes. This form of anticipatory adaptation not only helps in bacterial survival but also contributes to the broader ecological resilience of these microorganisms.

Reference

John Innes Centre. Ice bucket challenge' reveals that bacteria can anticipate the seasons. Science News. Available at- https://www.sciencedaily.com/releases/2024/09/240906141743.htm

(Accessed: 10 September 2024)