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Final bio lab report based off moldy bread experiment...

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3-09-2020 Biology II D03

Temperature effects on fungal growth

Abstract The main purpose of this experiment was to analyze if temperature had an effect on fungal growth on the bread. In the experiment the breads were placed in three different environments, 5 in room temperature, 5 in the refrigerator and lastly 5 were placed in a humid environment. The results were measured and documented every 3rd day for 21 consecutive days. The findings of the experiment showed that the breads placed in the colder environments had less mold growth in comparison to the breads placed in a humid environment and room temperature. The findings also showed that the amount of mold covered on the bread were very similar in both humid and room temperature.

Introduction The distinct mold that grew on the bread was discovered to be Rhizopus Stolonifer, which is most known as black bread mold. This specific mold is a part of the phylum Zygomycota, it is known to be the most important species in the genus Rhizopus. It is known to also be the most well known fungi that will grow on a variation of food all over the world. Artificial preservatives are placed on food in order to preserve them longer from spoiling, if a bread was chosen that was known to have preservatives it would not have spoiled in the 21 day time frame allotted by the instructor. Temperature is also a crucial contributor to mold growth on the bread. The low pH of most fruits is generally not common for the growth of bacteria,

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however different molds can still grow on fruits and cause them to rot. In the first stage of the mold life cycle, the mold lays dormant on the bread as a spore. However, when the spores find a moist and warm area they will grow and gain more and more spores (Reynolds, L. 2019). The hypothesis that was made at the beginning of this experiment was “Humidity will increase the amount of fungus growth on the bread.” The main purpose of this experiment was to gather and analyze the rate of mold growth on breads placed in different environments.

Methods: The main objective of this experiment was to identify which condition produced the most mold on the bread in the selected time frame of 21 days. The experiment was accomplished by collecting 15 pieces of bread and labeling 15 bags. The bags were labeled according to what environment they were placed in. For example, for the refrigerated condition they were labeled R1, R2, R3, R4, and R5. Each bag would have a 10 *10 cm grid on the outside and the breads would be cut in order to appropriately fit the grid. Also before the breads were placed in their designated conditions/ bags they needed to be laid out at room temperature in order to ensure that any of the fungal spores in the air will settle in the bread. For the humidity samples each piece of bread was scattered with 1 teaspoon of water in order to create a humid environment when placed in the bag. It was ensured that the samples which were placed in a cabinet that was frequently opened, just as much as the refrigerator. The samples were looked at and documented every 3rd day for 21 consecutive days in order to properly document the progression of mold on the breads.

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Results The mean for the room temperature and humid samples of bread came to be the same which were 100%,. However, the refrigerated samples mean came to be 0%. The standard deviation for the room temperature came to 3.3, humidity sample came to be 3.9, while the refrigerated sample was 0. When you use all of the standard deviations and the degrees of freedom which was 4, you can conclude the significance level that came to be about 25%. The significance level can be used to find the critical T- value which concluded to be 1.789.

This chart shows the mold growth of the different breads throughout the 21 day experiment that took place in the room environment, fridge environment and humid environment.

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Discussion In this experiment it was concluded that temperature does in fact affect mold growth on the pieces of bread. It was concluded that the breads placed in colder environments were subjected to less mold growth in comparison to the breads placed in a humid/ room temperature environment. There was a significance difference in this experiment because the significance value came out to be 25%, which resulted in a T- value of 1.789 which would justify the hypothesis made at the beginning of the experiment. The hypothesis was “Humidity will increase the amount of fungus growth on the bread.” Some of the errors which were made in the experiment would be that the refrigerator might not have been opened as much as the cabinet, which means that not as much air flow is going into the cabinets and less mold will consequently grow (Legan, J. 2002). A study (mold growth, 2020) compared mold growth when placed in higher and lower temperatures. They placed five pieces of bread in a warm environment, and the other 5 in a refrigerator. They concluded that when the bread is placed in a cold environment there would be less mold growth. Another study exclusively looked at the effect of humidity on mold growth (Tang W, Kuehn TH, Simcik MF. 2015). They distributed 1 tablespoon of water on three pieces of bread then placed them in sandwich bags, they compared it with 3 pieces of bread just placed in bags without water. They also put the bread in the same cabinet together. They concluded that a humid environment does allow for more rapid growth of mold on bread.

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References Mold growth. (2020, August 12). Retrieved March 09, 2021, from https://energyresearch.ucf.edu/consumer/buildings/building-science-basics/mold-growt h/ Lakins, D., Echeverry, A., Alvarado, C., Brooks, J., Brashears, M. and Brashears, M. (2008), Quality of and Mold Growth on White Enriched Bread for Military Rations Following Directional Microwave Treatment. Journal of Food Science, 73: M99-M103. https://doi.org/10.1111/j.1750-3841.2008.00677.x Legan, J. (2002, November 13). Mould spoilage of bread: The problem and some solutions. Retrieved March 09, 2021, from https://www.sciencedirect.com/science/article/abs/pii/0964830593900384 What causes the growth of bread mold and how to prevent it? (2010, April 07). Retrieved March 09, 2021, from h  ttps://biologywise.com/bread-mold-growth Reynolds, L. (2019, March 02). How does MOLD grow on Bread? Retrieved March 09, 2021, from h  ttps://sciencing.com/mold-grow-bread-5403099.html Says:, M., Says:, L., Says:, S., Says:, S., Says:, P., Says:, Z., & Says:, E. (2020, April 18). Why does Bread get moldy? - the science of BREAD SPOILAGE. Retrieved March 09, 2021, from https://foodcrumbles.com/why-bread-gets-moldy-spoilage-of-bread/ Mold bread experiment. (n.d.). Retrieved March 09, 2021, from https://explorable.com/mold-bread-experiment Tang W, Kuehn TH, Simcik MF. Effects of Temperature, Humidity and Air Flow on Fungal Growth Rate on Loaded Ventilation Filters. J Occup Environ Hyg. 2015;12(8):525-37. doi: 10.1080/15459624.2015.1019076. PMID: 25849091. “Bio II Lab manual (2020)”. The moldy bread lab- Fungus Among Us. Nova Southeastern University Biology Department Reece, J.B., Urry, L.A., Cain, M.L., Wasserman, S. A., Minorsky, P.V., Jackson, R., & Campbell,

 ew York: Pearson Education. N.A. (2014) Campbell Biology. N

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