Cyanobacterial Culture Synchronization and DNA Compaction Driven by Light-Dark Cycles

Begin with a nutrient-rich agar plate supplemented with thiosulfate.

Streak the cyanobacteria and incubate under alternating light and dark periods to maintain the circadian cycle.

During the light period, nutrient uptake and thiosulfate support bacterial growth and the condensation of DNA.

In the dark period, the cells conserve energy and divide.

The alternating light-dark cycle synchronizes cells to the same stage of growth and division.

After the light period, add a sucrose solution and pipette repeatedly to release cyanobacteria, causing a color change. Transfer the cells into a tube.

Add a DNA-specific fluorescent dye and incubate in the dark. The dye binds to the cyanobacterial DNA.

Centrifuge to separate the cyanobacteria and remove the supernatant.

Resuspend the cyanobacteria in sucrose solution, transfer the suspension to a slide, and cover it.

Under a fluorescence microscope, the blue condensed DNA in cells confirms the synchronized, circadian-regulated progression of the cyanobacterial cell cycle.

Begin with growing cyanobacteria on nine-centimeter, sterilized BG-11 plates containing 1.5% agar and 0.3% sodium thiosulfate. Incubate the plates at 23 degrees Celsius under a 12-12 lig