How the Type and Wavelength of Light Affects the Amount of Mold Growth on White Bread By: Ben Griffiths, Kenny Aronson, and Mark Walker

Introduction Rationale to see what environmental variables affect mold growth Needs spores to be on food Grows on food source Purpose to find out which type / color of light affects mold growth Hypothesis: no light will yield the most mold

Light Wavelengths Atoms release energy and photons Different wavelengths of light Only some can be seen UV is higher wavelength X-rays are a few millionths of a mm UV has more energy Can cause molecules to break apart Killing mold etc

Black light (UV)White lightBlue lightRed lightNo light 1 trail Experimental Design IV: the type of light, i.e., Black, white, blue, red, and no light DV: the amount of mold that grows on the bread Constants: The types of light (black,white, blue, red, none) The time exposed to light (constant exposure, lights never off) Amount of water put on bread per application (dependant on day) The type of bread (white bread) Amount of bread (full petri dish) Temperature and humidity of room (room defined) Where samples were placed (similar cabinets) The length of the experiment Number of trials per type of bread (1)

Procedure 1. Obtain all necessary equipment. Bread, 5 Petrie Dishes, 3 Lamps, 1 Black Light, 2 Color Filters (red and blue), Graduated Cylinder, Camera 2. Size the bread so that it fits tightly in the Petrie dishes. 3. Take a picture of each dish. This represents the day 0 observation. 4. Cover 2 of the white light lamps with the colored filters so that they are each a different color. 5. Find 5 separate cabinets or dark places in which the dishes can be stored where they will not be destroyed. 6. Put a different bread sample in each place and set up the lamps so there is one with black light, white light, blue light, red light, and one with no light. 7. For the first observation period leave the bread uncovered so that it can collect mold spores. 8. After each period, take a picture of each sample, labeling the day as well. 9. Add appropriate amount of water to each bread sample to remoisten it after every observation. Be sure to keep the amount constant for each sample.

Results Black light No light White light Blue light Red Light

Day 0

Day 3

Day 5

Day 12

Micro specimens Zygomycetes Rhizopus Deuteromycetes Penicillium 2-5 μm Blue, Red, No LightWhite, Red, No Light

Micro specimens Deuteromycetes Aspergillius 2-5 μm Zygomycetes Mucor White Light

Conclusion UV Light yielded least mold Light color with same kind of source made no difference No light produced about the same amount of mold Would use fluorescent next time