Science Project Zhivko illeieff Draft How high temperature affects bacteria growth? Introduction The point of this experiment is to see if the temperature of pasteurization (160 degrees F.) would eliminate a specific kind of bacteria. In my case it is Escherichia Coli K-12. (….Note: I am going to put some information about E Coli after that last sentence). I am going to label each of the tubes used as either 1,2,3,4 or 5. In the end, I would end up with 4 tubes for each number. Each of those numbers would be heated at different times. Hypothesis The higher the temperature gets, the more bacteria will be eliminated. Materials - Tubes (for the cultivation of bacteria) -hot water bath (for heating the tubes) -aluminum foil (used for sealing the tubes) -pump (used for precisely putting the 2 tenths of a milliliter of bacteria) - Microscope (to make sure bacteria has cultivated) - Bunsen burner (sterilizing) - Nutrient sterol liquid (used for the environment ideal for bacteria growth) - Constant speed mixer (for suspending the liquid) Procedures Step 1 I put steroal nutrient broth in 14 small tubes and capped each one of them with aluminum foil. 4 of those tubes were used for the primary cultivation bacterial growth. The types of bacteria that were tried were: - Bacillus Megaterium - Bacillus Sereus - Esceridia Coli - Enterobacter Aerogenes Of them, I chose Escherichia Coli for the project assigned to me. Using a microscope “SWIFT M3200”, E. Coli looked rod-like. STEP 2 The remaining 10 tubes we used to cultivate the bacteria E. Coli. 2 tenths of a milliliter were put into each of those 10 tubes using a pump. Each one of them was sterilized with a Bunsen burner and suspended, so that the bacteria would be evenly disturbed in the nutrient sterol liquid. I chose to use the same temperature at different times. The constant temperature that the tubes were heated at was 160 degrees Fahrenheit or 71 degrees Celsius. Two of the tubes were labeled 1, two others were labeled 2, another two of the tubes were labeled 3, two others were labeled 4 and the remaining two tubes were labeled 5. The reason why I have two tubes for each number is that they both should have the same amount of bacteria in order for me to be sure that everything went according to plan. STEP 3 All ten of the tubes were put into a water bath, “Imperial 4” at the constant temperature of 71 degrees Celsius. The temperature varied from 70 degrees to 74 degrees. Tubes labeled number one were the control group, thus they were not heated. After 20 min I got out tubes number 2, after 40 min. tubes number 3, after 60 min. tubes number 4 and after 80 min tubes number 5. STEP 4 I repeated Steps 2 through 3 so that I would have 4 tubes for numbers 1,2,3,4 and 5. STEP 5 The last part of the experiment was to evaluate the amount of bacteria in each tube using the spectrometer. Notice that there are 4 numbers at the “%Transmittance” section and 4 numbers for the “Absorbance” section. That is, because each of those 5 numbers used 4 tubes. Tube Number Temperature HeatedHeated For %Transmittance Absorbance 1 (control) 71 Degrees Celsius 0 min. 55/32/ .27/.54 2 71 Degrees Celsius 20 min. 50/73/ .32/.14/ 3 71 Degrees Celsius 40 min. 32/55/ .53/.27/ 4 71 Degrees Celsius 60 min. 71/34/ .16/.48 5 71 Degrees Celsius 80 min. 70/37/ .16/.45
