All living organisms have specific nutritional and environmental requirements regardless of their size. In this experiment, you will identify the optimal conditions for cultivating fungal growth on bread and fruit. Any type of bread can be used, but fresh bakery bread will likely grow more colorful species because it does not contain the preservatives that many processed varieties do.
PROCEDURE
- Record the Purpose and your Hypothesis for this experiment in your assessment package.
- Use the permanent marker to label the ten plastic bags as follows:
• Bright – Control
• Bright – Water
• Bright – Corn Syrup
• Bright – Lemon
• Bright – Vinegar
• Dark – Control
• Dark – Water
• Dark – Corn Syrup
• Dark – Lemon
©2018, eScience Labs
• Dark – Vinegar
- Place a kitchen knife and cutting board on a sturdy surface, such as a tabletop or counter. Carefully cut the two slices of
bread into 10 pieces (5 pieces per slice). Then, cut the apple into 10 slices. - Place one piece of bread and one slice of apple into each plastic bag.
- Use the measuring spoon to measure and add 1 teaspoon of tap water into the bags labeled “water.” Then, seal the bags
closed. - Use the measuring spoon to measure and add 1 teaspoon of corn syrup into the bags labeled “corn syrup.” Then, seal the
bags closed. - Use the measuring spoon to measure and add 1 teaspoon of acetic acid into the bags labeled “vinegar.” Then, seal the bags
closed. - Use the measuring spoon to measure and add 1 teaspoon of lemon juice into the bags labeled “lemon.” Then, seal the bags
closed.
Note: Do not add anything to the bags labeled “control.” - Find a well-lit, warm location to place each bag labeled “bright.” This could be a sunny windowsill, under a lamp, etc.
- Find a dark, warm location to place each bag labeled “dark.” This could be a closet, near a heater with the lights off, etc. 11.Examine the bags ever 1 – 2 days for two weeks. Look for mold formation on the bread and apple pieces. Take particular
note of which environmental condition(s) the mold formed in first and last. Record your results in Table 1. - At the end of two weeks, rank the samples from 1 – 10 based on which grew the most mold (1) to which grew the least mold
(10). - Place 1-2 drops of water on the blank slide.
- Open one of the bags with mold growth just enough to insert the cotton swab. Gently rub the tip of the cotton swab against
an area of mold growth. - Swirl the cotton swab in the water on the blank slide.
- Allow the solution to completely air-dry (approximately 30 minutes). The smear should now appear slightly cloudy.
- Over a sink or disposable plastic container, saturate the sample with crystal violet, and wait 1 minute.
15.Rinse the slide with deionized water for 30 seconds.
18.Gently place the coverslip over the smear and paint the edge of the coverslip with the clear nail polish. Let the nail polish dry
completely. - Observe the smear under your microscope. Document your observations in the post-lab questions. Take a photograph of the
slide through the microscope eyepiece and submit the image to your instructor. - When finished with the experiment, do not open the bags. This could disperse mold spores and contaminate your work/living
area. Dispose of the sealed bags in the trash, and remove the trash bag from your living area.
©2018, eScience Labs