In my research project yeast cells (mainly Saccharomyces cerevisiae) goes under the UV-lamps. Ultraviolet light is an electromagnetic radiation with a wavelength from 10 nm to 400 nm from which I am using 365-405nm. Cells go under these death rays and this probably causes lot of stress for them. The exposure time for the yeastograms varies from 36 up to 70 hours. Lenght of time depends on the temperatures outside.
Exposure mainly happens in a old wooden house in my studio which is very cold in winter (about 15°C in winter – 20°C in summer or more). The UV lights generates heat and makes the petridishes wet. Winter conditions gives them more stabile environment to tolerate the heat. Usually the wetness has been indicator that the yeast is working but new results prove that the image can form perfectly without the moisture.
UV light, in large quantities over longer periods of time, does kill yeast cells eventually. A 1920 study published in the “Botanical Gazette” noted that yeast does have a threshold after which it dies from overexposure to UV light. This threshold depends on the strength of the UV light source and the time of exposure.
The Effects of UV Light on Yeast,
Science studies with UV-light and yeasts have started early as 1920´s. By for example Fred W. Tanner.
Another source on how yeast behaves under the UV-lights is an article: The Effects of Ultraviolet Radiation on Yeast, By Timothy Banas.