Nathan+P

= = =**Bacteria in Milk**= = = = = =Question=

Does organic(raw) milk or pasteurized milk have more bacteria in it? Also, does the percent fat effect my results?

**Hypothesis**

If you test the number of bacteria in organic milk and in different types of pasteurized milk, then the organic milk will contain more bacteria. = = =**Science Fair Procedure**=

1. Loosen the cap on the agar bottle. 2. Microwave the bottle until it starts to boil and and check if it a liquid by swishing it around. 3. Let the bottle cool off before you pour so you don't burn your hands. 4. Pour a small layer of agar into the petri dishes. Just enough to cover the dishes. 5. Cover the petri dishes with their lids and let them set for a hour or two before putting them in the refrigerator upside down. 6. Sterilize the inoculation loop by burning it over a candle. 7. Use a method called streaking to spread the organic milk onto the surface of the agar in the petri dish using the inoculation loop. 8. To streak dip an inoculation loop into the organic milk and spread it across the petri dish. 9. Once all the milk is spread evenly on the petri dish, properly seal the dish with Parafilm so that no bacteria will escape. 10. Do steps 6 through 9 for all ten trials of the organic milk. 11. Place the petri dishes into an incubator for 2 to 3 days at 90 degrees Fahrenheit, 32 degrees Celsius. 12. Each day count the number and size of the colonies on the petri dishes and record the data. 13. Do steps 1 through 12 for the skim pasteurized milk, 2% pasteurized milk and the whole pasteurized milk. 14. When finished with petri dishes they should be properly disposed of by sending them to be auto-claved which will destroy the bacteria.

=**Materials List**=

Whole pasteurized milk Skim pasteurized milk 2% pasteurized milk Organic milk 40+ petri dishes Incubator Parafilm Sterile inoculation loop Microwave Agar Candle Lighter Sizzors Permanent Marker

=**Data and Observations**=

10/20/10- I talked to Mr. Lloyd to see if I had to buy my own agar and petri dishes or if he could supply them. He told me I had to get my own supplies. I also asked him what to seal the petri dishes with and he said to use Parafilm.

That night I ordered petri dishes and agar on the Internet.

10/2510- The petri dishes and agar arrived. The petri dishes are smaller than what I thought but I will ask Mr. Lloyd if they are still OK.

10/26/10- I went to talk with Mr Lloyd and asked him if he would supply the inoculating loop and to see if the petri dishes were the right size. He went over to talk with Mrs. Fogell and she said the petri were fine and that I could use her inoculation loop. She also suggested that I use LB broth instead of agar.

I ordered for the Parafilm that night and decided to use the LB broth instead of the agar.

10/27/10- I talked with Mrs. Fogell about the broth and how to prepare it. Since I am using broth I changed my materials list and my procedure.

10/29/10- My Parafilm arrived.

11/1/10- During lunch I prepared the broth and poured it into 10 petri dishes following steps 1 through 6 in my procedure.

11/2/10- I checked to see if the broth set overnight but it was still a liquid so I couldn't use it. Mr Lloyd and Mrs. Fogell both said that the directions on the broth were probably incorrect. For the rest of the lunch period I made 10 new petri dishes using the agar that I had in backup. I will use agar instead of broth so I changed my procedure and material list again.



After school I went down and saw that my agar set properly. I then did steps 6 through 11 of my procedure with the 2% pasteurized milk which will be my first test.



11/3/10- I checked on the petri dishes to see bacteria growth. I started my 2% Pasteurized Milk table of data recording day one.

8 medium colonies || a 2cm colony 7 medium colonies || 3 medium colonies || 4 medium colonies 3, 1/4 cm colonies || 4, 1/2cm colonies 3 medium colonies || a 3/4 cm colony || a 1/3cm colony a 1cm colony || a 1/3cm colony || 5 small colonies 4 elongated colonies || 8 medium colonies 9, 1/4cm colonies a 1cm amoeba colony || 8, 1/4cm colonies 8 medium colonies a 1cm amoeba colony || 35 small colonies || 23 medium colonies 25 small colonies 1 inch crystal like colony || 8, 1/4cm colonies 11 medium colonies 16 small colonies a 3cm crystal like colony || 2 long skinny colonies 3 medium colonies || 3, 1cm amoeba colonies 4 medium colonies || 3, 1cm amoeba colonies 6medium colonies || 1 long skinny colony || 2, 1/4cm amoeba colonies 2, 1 inch skinny colonies a 2 inch skinny colony 3, 1cm skinny || 2, 1/4cm amoeba colonies 2, 1 inch skinny colonies a 2 inch skinny colony 3, 1cm skinny || several small dots || a 1/4cm colony several small dots || a medium colony is a couple mm. a small colony is a tiny dot.
 * **2% Pasteurized Milk** || Day 1 || Day 2 || Day3 ||
 * Trial 1 || 2 small colonies || a 1 1/2 cm colony
 * Trial 2 || 6 small colonies
 * Trial 3 || 1 medium
 * Trial 4 || 11 medium colonies
 * Trial 5 || 16 medium colonies
 * Trial 6 || a 3/4 cm amoeba shaped colony
 * Trial 7 || 2 large 1/2 cm colonies
 * Trial 8 || 1 medium colony || a 1/4cm colony
 * Trial 9 || a 1/2 cm colony || a 1/2cm colony || a 1/2cm colony ||
 * Trial 10 || 1 medium colony || 1 medium colony || 1 medium colony ||

11/4/10- I checked on the petri dishes and added data to my 2% Pasteurized Milk table by recording day two.

11/5/10- I checked on the petri dishes and added data to my 2% Pasteurized Milk table by recording day three.

I will redo Trials 8, 9, and 10 because It looked like I smeared too much milk on them. They were one of the first ones I streaked.

I ordered more petri dishes.

11/7/2010- I made 20 new petri dishes by following steps 1 through 5 at my house.

11/8/2010- During lunch I prepared the 10 petri dishes using steps 6 through 11 for my tests of the fat free milk.

My extra petri dishes came.

11/9/2010- I recorded the results my bacterial growth after day 1.

1 medium ||  || 2 small ||  || 4 small || one 2/3 cm amoeba 3 medium 5 small one 1/4 cm ||  || one 1/4cm one 1/3 cm 3 small || 2 medium 5 small one 1/4 cm one 1.5 cm crystal one 1/2 cm ||  || one 1 cm 2 small || one 1 cm six 1/4 cm ||  || 4 small one 1 cm skinny ||  || 1 medium || 1 medium 3 small ||  || one 1cm crystal || one 1/4 cm 3 medium 9 small one 2 cm crystal ||  ||
 * **Fat Free Pasteurized Milk** || Day 1 Colonies || Day 2 Colonies || Day 3 Colonies ||
 * Trial 1 || 1 medium || one 1/4 cm
 * Trial 2 || nothing || 1 small ||  ||
 * Trial 3 || 4 medium || 5 medium
 * Trial 4 || one 1/4 cm amoeba
 * Trial 5 || 3 medium
 * Trial 6 || one 1/4 cm
 * Trial 7 || 8 small || 8 medium
 * Trial 8 || Redo || Redo ||  ||
 * Trial 9 || 1 small
 * Trial 10 || 5 small

11/10/2010- I recorded the results my bacterial growth after day 2.

11/11/2010- I was going to record the results my bacterial growth after day 3 but Mr. Lloyd decided to tell me that on Monday he noticed that the incubator wasn't on. I checked the temperature of the incubator and it was too much of a difference so I will have to redo that week.

11/14/2010- I made 11 new petri dishes using steps 1 through 5 of my procedure at my house.

11/15/2010- I prepared my 10 petri dishes that will use to redo my fat free milk test and I also prepared the 3 petri dishes that I will use to redo trials 8, 9, and 10 of my 2% milk test. I prepared all of them using steps 6 though 11 and made sure that the incubator was on.

11/16/2010- I went down during lunch to check on my petri dishes but I noticed not much grow on any of them. I checked the temperature and it was higher than my 2% milk test. I still recorded my data and turned down the temperature a little.

1 small || 3 medium 1 small || 1 medium || one 1/2 cm one 1/4 cm 1 small || one 1/4 cm || one 1/4 cm one 2/3cm || 3 medium 3 small || three 1/4 cm 3 medium 6 small || two 1/3 cm three 1/4 cm 8 medium 5 small || 2 medium 5 small ||
 * **Fat Free Milk Redo** || Day 1 Colonies || Day 2 Colonies || Day 3 Colonies ||
 * Trial 1 || nothing || nothing || nothing ||
 * Trial 2 || 1 medium || 1 medium
 * Trial 3 || 1 medium || one 1/4 cm
 * Trial 4 || redo || redo || redo ||
 * Trial 5 || redo || redo || redo ||
 * Trial 6 || nothing || nothing || 2 small ||
 * Trial 7 || two 1/4 cm || one 1/2 cm
 * Trial 8 || 3 medium || redo || redo ||
 * Trial 9 || two 1/4 cm
 * Trial 10 || 1 medium || one 1/4cm || one 1/4cm

1 small || 1 medium 2 small || 2 small || one 1/4 cm 4 small || one 2/3 cm- 2 small absorbed 2 small 2 small ||
 * **2% Milk Redo** || Day1 Colonies || Day 2 Colonies || Day 3 Colonies ||
 * Trial 8 || 1 small || 1 small || 1 small ||
 * Trial 9 || 1 small || 1 medium
 * Trial 10 || 1 medium

11/17/2010 I recorded my data after day 2 but there was still not much bacterial growth.

11/18/2010 I recorded my data after day 3. Mr. Lloyd and I talked and we agreed that the temperature in the incubator was not staying constant and he suggested that I use another incubator.I decided that I should redo my entire experiment.

11/21/2010- I ordered for more petri dishes.

11/23/2010- I asked Mrs. Fogell if I could use her incubator for my experiment and she gave me permission to use it. She has a new and more reliable incubator. I also have decided to test all 40 petri dishes of my experiment at the same time so they all have the same conditions to grow in providing more reliable results.

11/24/2010- My new petri dishes came.

12/2/2010- I told Mrs. Fogell that will need the incubator the next week when I will do all of my experimenting. I also got the inoculation loop from Mr Lloyd.

12/3/2010- I called up my grandfather and told him that I needed the raw milk by tomorrow. He is a farmer and will go to one of his neighbors to get the milk.

12/4/2010- I went over to my grandparents house and picked up the raw milk.

12/5/2010- During the morning following steps 1 through 5 of my procedure I made the 40 petri dishes that I will use for my new experiment.



During the afternoon I went and bought the pasteurized two percent, whole and fat free milk.

In the evening I streaked the one of each of my four different types of milk using steps 6 through 10 of my procedure.

12/6/2010- I placed the four petri dishes in the incubator that was set a 89 degrees Fahrenheit. I will only test 4 for the first day so I make sure that this trial will be a success before I put the other 36 petri dishes in.

That night I streaked the other 36 petri dishes using steps 6 through 10 of my procedure.

12/7/2010- I put the rest of the 36 petri dishes in the incubator and recorded the results of the four trial ones on my final redo organic milk table, and final pasteurized whole, fat free and two percent milk tables.



1 medium 2 small || a 1/2 cm three 1/4 cm 1 medium 10 small || a 1 cm a 1/2 cm two 1/4 cm 12 medium 12 small || 57 small || 22 small || a 1/4 cm 8 medium 40 small || 30 small || 60 small || 18 small || 10 medium 36 small || 25 small a 1/4 cm || a 1/4 cm 7 medium 45 small || 10 medium 28 small || 3 medium two 1/3 cm || two 1/2 cm 10 medium 35 small ||
 * **Final Pasteurized**
 * Fat Free Milk Table** || Day 1 Colonies || Day 2 Colonies || Day 3 Colonies ||
 * Trial 1 || a 1/4 cm
 * Trial 2 || 2 medium || 42 small || 2 medium
 * Trial 3 || 1 small || 2 medium
 * Trial 4 || 1 small || 18 small || 6 medium
 * Trial 5 || 2 small || 46 small || 10 medium
 * Trial 6 || nothing || 4 medium
 * Trial 7 || 8 small || 3 medium
 * Trial 8 || 2 small || 3 medium || a 3 cm
 * Trial 9 || two 1/4 cm || 30 small
 * Trial 10 || redo || redo || redo ||

3 small || 25 small || redo || redo || 10 medium 50 small || four 1/4cm 6 medium 62 small || four 1/4 cm 3 medium 60 small || 55 small || a 1/3 cm 55 small || 55 small || six 1/4 cm 24 medium 50 small || seven 1/4 cm 20 medium 60 small || 4 medium 100 small || Eight 1/4 cm 8 medium 90 small || eight 1/4 cm 10 medium 80 small || 3 small || a 1/4 cm 3 small || a 1/3 cm 6 small || 70 small || a 1/2 cm two 1/4 cm 13 medium 40 small || a 1/2 cm three 1/4 cm 12 medium 60 small ||
 * **Final Pasteurized**
 * Two Percent Milk Table** || Day 1 Colonies || Day 2 Colonies || Day 3 Colonies ||
 * Trial 1 || 1 small || 1 small || a 1/4 cm
 * Trial 2 || 15 medium
 * Trial 3 || 21 small || redo || redo ||
 * Trial 4 || a 1/4 cm
 * Trial 5 || 60 small || a 1/3 cm
 * Trial 6 || 5 medium
 * Trial 7 || Three 1/4 cm
 * Trial 8 || 1 medium
 * Trial 9 || a 1/2 cm
 * Trial 10 || 2 small || redo || redo ||

2 medium 4 small || 9 small || 5 small a 6 by 1 cm rectangle || 5 small || 3 medium 4 small || 7 small 1 medium || two 1/4cm 5 medium 5 small || 2 medium || seven 1/4 cm two 1/3 cm 9 medium 8 small || a 1 cm three 1/3 cm three 1/4 cm 10 medium 60 small || a 1/4 cm 1 medium || a 1/4 cm 2 medium 3 small || two 1/4 cm 3 medium 3 small || 2 small || four 1/4 cm 1 medium 42 small || a 1cm three 1/4 cm 9 medium 70 small || 3 small || a 1/4 cm 3 small || a 1/3 cm 1 medium 3 small || 1 small || a 1 1/2 cm four 1/4 cm 12medium 27 small ||
 * **Final Pasteurized**
 * Whole Milk Table** || Day 1 Colonies || Day 2 Colonies || Day 3 Colonies ||
 * Trial 1 || 2 small || 2 small || a 1/3cm
 * Trial 2 || 4 small || 8 small || 4 medium
 * Trial 3 || 1 small || 3 small || a 3 by 1 cm rectangle
 * Trial 4 || 2 small || 1 medium
 * Trial 5 || 3 small || a 1/4 cm
 * Trial 6 || 9 small
 * Trial 7 || 2 small
 * Trial 8 || a 1/4 cm
 * Trial 9 || 1 medium
 * Trial 10 || 2 small || a 1cm

a 2/3 cm 80 small || four 1 cm five 2/3 cm a 1/4 cm 15 medium 60 small || a 1 1/2 cm eight 1 cm a 2/3 cm a 1/4 cm 11 medium 50 small || 20 medium 200 small || Fifty four 1/4cm 8 medium 200 small || fifty five 1/4 cm 220 small || 7 medium 150 small || twenty 1/4 cm 20 medium 170 small || twenty three 1/4 cm 22 medium 180 small || 70 small || twenty seven 1/4 cm 10 medium 100 small || twenty seven 1/4 cm four 1/3 cm 17 medium 110 small || 140 small || Thirty five 1/4 cm 5 medium 180 small || thirteen 1/4 cm twenty four 1/3 cm 13 medium 200 small || 12 medium 120 small || seventeen 1/4 cm 9 medium 140 small || five 1/3 cm thirteen 1/4 cm 12 medium 140 small || 10 medium 140 small || three 1/3 cm thirteen 1/4 cm 10 medium 140 small || Twelve 1/2 cm four 1/4 cm 160 small 19 medium || seven 1/4 cm 80 small 15 medium || ten 1/3 cm 9 medium 75 small six 1/4 cm || four 1/2 cm fourteen 1/4 cm 90 small || 7 medium 60 small || two 1/2 cm two 1/4 cm 17 medium 65 small || 17 medium two 1/2 cm 3 red medium seven 1/4 cm 60 small || nine 1/4 cm 52 small || three 1/3 cm nine 1/4 cm 8 medium 70 small || four 1/3 cm eight 1/4 cm 8 medium 70 small || ---Raw Milk, Whole Milk -2% Milk
 * **Final Organic(Raw)**
 * Milk Table** || Day 1 Colonies || Day 2 Colonies || Day 3 Colonies ||
 * Trial 1 || seven 1/2 cm
 * Trial 2 || Thirty three 1/4 cm
 * Trial 3 || Twenty two 1/4 cm
 * Trial 4 || Twenty four 1/3 cm
 * Trial 5 || Thirty 1/4 cm
 * Trial 6 || fourteen 1/4 cm
 * Trial 7 || fifteen 1/4 cm
 * Trial 8 || nine 1/3 cm
 * Trial 9 || two 1/3 cm
 * Trial 10 || 6 medium

Fat Free Milk Organic Milk with Red Colonies

12/8/2010- I recorded my trial 1's for day 2 and the rest of my trials for day 1 on my Final Pasteurized Fat Free Milk, Final Pasteurized Two Percent Milk, Final Pasteurized Whole Milk, and my Final Organic(Raw) Milk Tables.

I noticed that the 2% pasteurized milk had more bacteria after the first day so I checked the date when the milk expires. 2% expires on 12/14/2010, the whole milk on 12/18/2010, and fat free milk on 12/19/2010.

12/9/2010- I recorded my trial 1's for day 3 and the rest of my trials for day 2 on my Final Pasteurized Fat Free Milk, Final Pasteurized Two Percent Milk, Final Pasteurized Whole Milk, and my Final Organic(Raw) Milk Tables.

12/10/2010- I recorded the rest of my trials for day 3 on my Final Pasteurized Fat Free Milk, Final Pasteurized Two Percent Milk, Final Pasteurized Whole Milk, and my Final Organic(Raw) Milk Tables.

I gave the petri dishes to Mrs. Fogell to get auto-claved.



12/12/2010- I prepared the four redo petri dishes using steps 1 through 5 of my procedure. When they were hardening I when out and got the fat free milk and the 2% milk. Then using steps 6 through 9 of my procedure for all four petri dishes I streaked them.

12/13/2010- I placed the redo petri dishes in the incubator.

12/14/2010- I recorded the redo trials in the in Final Redo Table for day 1.

1 small || a 1/4 cm 3 medium 2 small || 2 medium 3 small || a 1cm a 1/4cm 1 medium 1 small || a 2 cm a 1/3 cm 3 small || a 1/4 cm || a 1/4 cm 3 small || a 1/3 cm 4 small || 2 medium || two 1/4 cm 3 small || two 1/2 cm a 1/4 cm 3 small || 12/15/2010- I recorded the redo trials in the in Final Redo Table for day 2.
 * Final Redo Table || Day 1 Colonies || Day 2 Colonies || Day 3 Colonies ||
 * Fat Free Trial 10 || 2 small || 1 medium
 * 2% Trial 2 || a 1/3 cm
 * 2% Trial 3 || 1 medium
 * 2% Trial 10 || 3 small

12/16/2010- I recorded the redo trials in the in Final Redo Table for day 3.

Lastly I gave Mrs Fogell the petri dishes so she can auto-clave them.

Pasteurized Milk || 2.1 medium or small .3 1/4cmor 1/3cm || 22.9 medium or small .6 1/4cm or 1/3cm .1 1/2 or larger || 42.3 medium or small .5 1/4cm or 1/3cm .8 1/2 cm or larger || 22.4 medium or small .5 1/4cm or 1/3cm .3 1/2cm or larger || 23.2 || .6 1/3cm or 1/4cm .1 1/2 cm or larger || 35.8 medium or small 2.6 1/3cm or 1/4cm .2 1/2cm or larger || 37.9 medium or small 2.8 1/3cm or 1/4cm .2 1/2 cm or larger || 36.9 medium or small 2.0 1/3cm or 1/4cm .2 1/2 or larger || 39.1 || .2 1/3cm or 1/4 cm || 9.6 medium or small 1.6 1/3cm or 1/4 cm .1 1/2cm or larger || 23.9 medium or small 1.9 1/3cm or 1/4cm .5 1/2cm or larger || 12.3 small or medium 1.2 1/3cm or 1/4cm .2 1/2cm or larger || 13.7 || 16.5 1/3cm or 1/4cm .8 1/2 cm or larger || 131.1 medium or small 20.0 1/3cm or 1/4cm 1.0 1/2cm or larger || 140.2 medium or small 20.2 1/3cm or 1/4cm 2.8 1/2cm or larger || 129.0 small or medium 18.9 1/3cm or 1/4cm 1.5 1/2 or larger || 149.4 ||
 * Final Averages || Day 1 Colonies || Day 2 Colonies || Day 3 Colonies || Average of all Three Days || Total average Colonies ||
 * Fat Free
 * 2% Pasteurized Milk || 37.0 medium or small
 * Whole Pasteurized Milk || 3.4 medium or small
 * Organic(Raw) Milk || 115.7 small or medium

**Works Cited** Bailey, Regina. “Bacterial Reproduction” // About. // New York Times Company. 2010. Web. 9 Oct. 2010. Deshpande, Amurta. “Pasteurized Milk.” // Buzzle. // n.p. 8 July. 2010. Web. 3 Oct. 2010. “Milk Pasteurization Guarding Against Disease.” // Furthering Families. // Michigan State University. n.d. Web. 9 Oct. 2010. Smith, S.E. “What is Pasteurized Milk?” W // isegeek. // n.p. 8 Sept. 2010. Web. 3 Oct. 2010. “The Pasteurization Process.” // Raw Milk Facts // White Tiger Productions. 21 Aug. 2010 Web. 9 Oct. 2010. “Agar Plate.” // Wikipedia. // Mediawiki. 7 Oct. 2010. Web. 10 Oct. 2010. U. Michelle. “The Effect of Various Pasteurization Temperatures on Bacterial Growth.” // Selah School District. // n.p. 2005 Web. 11 Oct. 2010. “Types of Bacteria found in Milk.” // Scribd. // Examville. n.d. Web. 9 Oct. 2010. “Nutrient Agar.” // Becton, Dickinson and Company. // n.p. 2010. Web. 9 Oct. 2010. Parmar, Nagina // “ // Bacterial Growth.” // Wikipedia //. Mediawilki. 1 Oct. 2010. Web. 10 Oct. 2010.