Course Hero Abstract E. coli

Comparing Escherichia Coli (E. Coli) Population Growth in Different Temperatures Escherichia Coli also known as E. Coli are prokaryotes which have its own set of functions different from animals, however, they are still living creatures and have optimal living spaces in which they prefer just like any other living organism. There are many conditions which causes bacteria to not work at their most optimal like changes in pH, temperature, resources, etc. Too basic or acidic of a pH or too high of a temperature will denature the proteins within the bacteria and cause the proteins and enzyme to not work as well (Ratkowsky, Olley, Ross 2004). In that case the reasoning behind this experiment is to compare the population growth of E. Coli in different temperatures such as 20C, 30C 37C and 40C to see if there is a significant different between the growth populations. E. Coli has an optimum temperature of 37C; therefore, it should have the highest grow (Albrecht 2018). If we can understand the best temperature at which a bacteria can grow, it will help many different professions within their work force to prevent the spread of bacteria. For example, food workers that want to prevent the spread of bacteria to not contaminate their customers. Question & Hypothesis: With previous knowledge about living organisms, we wonder if there are differences within growth in E. Coli within different environmental temperatures. We hypothesize that there will be a significant difference in growth between 20C, 30C, 37C, 40C and with further observation be to observe that 37C is prime temperature at which E. Coli reproduces best at. To start our experiment, everyone’s group was assigned a specific temperature in which we had to observe from. There would be different flasks of E. Coli incubating in different

temperature baths. There would be eight different flasks in total, four of which were our controls that contained just soy broth and the other four would be our experimental flask which contained E. Coli and soy broth. Sets of two flasks, one control and one experimental would each sit in the water bath incubating a specific temperature of 20C, 30C, 37C and 40C for a total of 14 hours, starting at 7:00 and ending at 21:00. When collecting our data, we would first calibrate the spectrophotometer by using a pipet to collect a small amount of the control broth and use that to zero the system. We would then repeat the process of collecting our data by always stirring the flask and then collecting a small amount of the experimental broth and observing the absorbance three times every hour. We collaborated with other groups to collect the full set of data that we needed which was all three samples of each broth at each temperature at each hour. After the readings were completed, we performed a two-way ANOVA. In this lab we compared the absorbance level of E. Coli to determine the difference in population growth in different temperature environments. Table 1 showcases the processed data of our raw data. This processed data contains the averages of absorbance of E. Coli of each test preformed on each temperature. The higher the absorbance the darker the solution, meaning that the growth of the E. Coli is also large. When looking at Table 1, we can see that the average absorbance levels for 37C is larger than the three other temperatures 20C, 30C and 40C. The average absorbance of each test in 37C are 0.18, 0.17 and ,0.17. We can also see that 20C had the least amount of E. Coli growth with 0.11, 0.12 and 0.12 for absorbance. We can also see this trend in Figure 1, where 37C had the highest amount of absorbance with 30C being an extreme close second. Both 20C and 40C were lower in growth, 20C being the lowest. From this we can assume that 20C slowed down the growth of E. Coli whereas, 40C had denatured the bacteria instead. We know this because in the graph you can visually see the absorbance increasing but

Literature Cited: Albrecht, J. A. (2018, July 17). Escherichia coli O157:H7 (E coli). UNL Food. Retrieved October 29, 2022, from https://food.unl.edu/escherichinia-coli-0157h7-e- coli#:~:text=Growth%20conditions%3 A &text=Optimum%20Temperature%3A%2037%C 2%B0C%20(98.6%C2%BOF) Ratkowsky, D. A., Olley, J., & Ross, T. (2004). Unifying temperature effects on the growth rate of bacteria and the stability of globular proteins. Journal of theoretical biology. https://pubmed.ncbi.nlm.nih.gov/15652145/

Figures and Tables: Average Absorbance Over Time at Four Different Temperatures =—=20C ==30C 0.250 0.200 0.150 0.100 Absorbance (600 nm) 0.050 0.000 —37C =40C 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 Time Figure 1: Depicts the average absorbance of E. Coli of the three test for each temperature over the course of 14 hours. Table 1. Depicts the three absorbance of E.Coli over the course of 14 hours for four different temperatures at degrees C. Listed below are the averages, mode, median and St. Dev of each test for each temperature. | | 20C 30C 37¢ 40¢C Time A 8 c A B c A B C A B C 7:00 0.041 0.049 0.066 0.045 0.054 0.051 0.035 0.037 0.039 0.056 0.06 0.052 8:00 0.047 0.062 0.064 0.074 0.089 0.074 0.098 0.085 0.091 0.079 0.092 0.0875 9:00 0.086 0.084 0.084 0.093 0.11 0.105 0.104 0.102 0.105 0.12 0.124 0.123 10:00 0.081 0.081 0.083 0.131 0.125 0.117 0.122 0.115 0.144 0.129 0.121 0.135 11:00 0.09 0.09 0.099 0.141 0.136 0.121 0.159 0.152 0.155 0.126 0.14 0.133 12:00 0.108 0.111 0.103 0.147 0.152 0.149 0.166 0.157 0.159 0.127 0.133 0.137 13:00 0.112 0.12 0.123 0.164 0.161 0.164 0.178 0.161 0.166 0.156 0.158 0.153 14:00 0.128 0.128 0.125 0.176 0.179 0.169 0.198 0.1755 0.19 0.181 0.174 0.176 15:00 0.12 0.129 0.131 0.197 0.199 0.188 0.197 0.19 0.203 0.181 0.173 0.181 16:00 0.129 0.139 0.147 0.201 0.199 0.195 0.216 0.219 0.216 0.193 0.184 0.195 17:00 0.138 0.151 0.1465 0.204 0.214 0.204 0.2265 0.2205 0.225 0.183 0.189 0.189 18:00 0.147 0.163 0.146 0218 0215 0212 0.237 0.222 0.234 0.195 0.192 0.176 19:00 0.147 0.149 0.167 0.2265, 0.221 0.213 0.237 0.224 0.2315 0.195 0.195 0.185 20:00 0.165 0.156 0.171 0.235 0.227 0.214 0.239 0.225 0.229 0.188 0.179 0.175 21:00 0.157 0.155 0.168 0.24 0.235 0.223 0.242 0.229 0.231 0.182 0.187 0.175 Average 0.113066667 0.1178 0.121566667 | 0.166166667 0.167733333 0.159933333[0.176966667 0.1676 0.174566667 |0.152733333 0.1534 0.1515 Mode 0.147 0.199 0.237 0.181 0.176 Median 0.12 0.128 0.125 0.176 0.179 0.169 0.197 0.1755 0.19 0.181 0.173 0.175 _Standard Deviation | 0.037753839 0.036653201 0.036631791 | 0.060344152 0.055372075 _0.05492393 | 0.062841202 0.060094033 0.05979873 | 0.044420823 0.040568813 0.040735646