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Tracking Ph Level’s of Food Preferred by
Physarum Polycephalum
Deborah Belew, Lisa Green, Allison Janecko, Bethany Mackan,
Jessica Schleifer and Chris Wilkin
Kent State University Stark Campus, Department of Biological Sciences, North Canton ,Ohio USA
INTRODUCTION
What is Physarum Polycephalum?True slime moldLife process
How does it obtain food?Surrounds foodSecretes enzymes
Does Physarum polycephalum typically prefer food that is acidic or basic?
Our question:Given a choice in a controlled environment, would it prefer acidic, basic, or neutral foods?
We believe that Physarum polycephalum will seek out the oat mixtures that are most neutral in Ph level.
HYPOTHESIS
METHODS Tested several items for Ph level utilizing Ph testing strips
provided by the lab
Selected 5 items with varying Ph levels (Table 1)
Obtained a culture sample of Physarum polycephalum from culture dish provided by the lab
Removed a 1 square cm section from culture. Used test tube caps initially to cut out sections then utilized scalpel for transfer to new dish.
Discussed contamination with Dr. Bernstein. Decided transferring the slime mold with the sterilized scalpel provided less contamination. Kept dishes exposure to air to a minimum by uncovering dishes only during transfer.
PH LEVELS
Table 1: Examples displaying range of Ph levels
Used a set ratio (Table 2) of oats and variable ingredient in each mixture
METHODS CONTINUED
1/8 tsp water 1/8 tsp of item A ½ tsp oats
1/8 tsp water 1/8 tsp of item B ½ tsp oats
¼ tsp water ½ tsp oats
Table 2: Ratio of ingredients
Set up Petrie dishes
3 different samples in each dish each time Carved 3 pathways in agar from center to each sample Maintained a “control” sample within each of water/oats Dish stored in drawer for 2 – 4 days
Recorded data in journal & discussed next step
MILK OF MAGNESIA
Ph level 10
Active ingredient: Magnesium hydroxide
Inactive Ingredients: citric acid, D&C red#28, glycerin, sorbitol, sucrose, water, xanthan, gum.
(Medicinenet, 2008)
HOT SAUCE
Ph level 3
Ingredients:Peppers, vinegar, and salt
(Louisiana Pepper, 2008)
SILK SOY MILK Ph level 7.5Ingredients:
filtered water, whole organic soybeans, organic evaporated cane juice, calcium carbonate, natural vanilla flavor, sea salt, carrageen, vitamin A, palmitate, vitamin D2, riboflavin (B2), vitamin B12
(http://www.silksoymilk.com/Products/SilkSoymilkRefrigerated.aspx)
SCOPEPh level 5
Ingredients:15%WT/V Glycerin, Ethanol SD 40Benzoic Acid & Sodium Benzoate (act as buffers)
Cetylpyridinium chloride Sodium Saccharin
Domiphen Bromide FD&C Yellow # 5, FD&C
Blue #1, water
(Household Products, 2008)
SUNNY MEADOW EGGS
Ph level 8
Nutritional facts:calories 90total fat 5gsaturated fat 2gcholesterol 270mgsodium 80mg carbohydrates 1g diet fiber 0gprotein 8g
• ((www.dailyplate.com), Eggs Grade
A)
WATER (control)
Ph level 7 (neutral)
Nutrition Facts :Calories 0Fat 0Carbohydrates 0Protein
(Calorie Count, 2008)
PH LEVELS OF ITEMS
• Does not have an apparent preference for either acids or bases thus far.
• Decide to start 2 new experiments. – One with “likes” from test 1 & 2
• (Egg/oats, hot sauce/oats) & water/oats neutral control
– One with “dislikes” from test 1 & 2 • (water/oats, scope/oats) & water/oats neutral control
In the dish containing the “dislikes” it appears to travel along the side of the agar path and settle on the neutral water/oat sample. This data suggests that it does not like the base or the acid.
• In the dish containing the “likes” our slime mold appears to have moved directly to the egg/oats sample.
RESULTS
Appears to prefer the egg/oats sample thus farWhy? What does each part of the egg contain?
Decide to separate the yolk from the albumen & test the slime mold’s preference for either.
Figure 1: Diagram of egg structure (wicker.myweb.uga.edu/eggs)
Also run another test:Soy milk vs. egg Reassure the preference for the egg as opposed to the preference for oats mixed with any base, as milk & egg both test as bases.
New Results
In soy milk vs. egg:Slime mold went directly to the egg
In yolk vs. egg:Slime mold went directly to the yolk as opposed to the water/oats or albumen/oats mixtures.
Why does the slime mold prefer eggyolk over egg white ?
EGG YOLK VS. EGG WHITE
Egg white structure: 7/8 water, 1/8 protein, o fat, niacin, riboflavin, chlorine, magnesium, potassium, sodium and sulfur.
Egg yolk structure: 1/2 water, 1/6 protein, 1/3 fat, emulsifiers (lecithin), vitamins A,D and E
Figure 2: Grades of eggs (The United States Department of Agriculture, 2006)
Data suggests that the
ph level of the “food”
does not entice the
slime mold to select it
as much as the
nutrients available.
END RESULTS
Figure 3: Nutritional Daily Allowance Pyramid(www.ams.usda.gov)
TABLE 2: Data showing Ph levels & whether the slime mold preferred or disapproved of that item.
Variable Ph level Slime Mold Preferred?
Soy milk 8 no
Milk of magnesia 10 no
Scope 5 no
Hot Sauce 3 yes
Egg (scrambled) 8 yes
Egg yolk 6 yes
Albumen (Egg white)
7.6 no
Figure 2: Hot sauce vs. Scope
Figure 3: Contamination
What do eggs contain that the other bases tested did not?
Eggs become more alkaline in pH level as they age according to Oregon State University. How would the slime mold react to freshly laid eggs opposed to store bought eggs?
Would Physarum polycephalum react differently to egg
substitutes?
Did bacteria on the egg have a role in the outcome of the experiment?
Would maintaining a cooler temperature thwart bacterial growth & harbor a different result?
NEW QUESTIONS
•Choose several different types, grades, ages of eggs and egg substitutes.
•Select cleaner agar Petrie dishes
•Study samples under several different temperatures
•Increase our quantity of sample dishes
•Decrease the time exposed to air
•Take samples from the same initial culture
NEXT STEPS
http://food.oregonstate.edu/learn/egg.html , Date accessed 12/2/08
REFERENCES
http://www.baking911.com, Date accessed 2008
http://www.dailyplate.com, The Daily Plate website for nutritional and dieting information “ Nutritional Information on the Egg, Date accessed 11/20/2008
Vadehra, D.V. and K.R. Nath. 1973. Eggs as a source of protein. CRC Critical Reviews in Food Technology 4: 193-309
http://lwicker.myweb.uga.edu/eggs_files/image004.jpg, Date accessed 11/30/08
The United States Department of Agriculture, “The United States Standard, Grades, and Weight Classes for Shell Eggs.” July 20, 2000. Date accessed 11/20/ 2008
http://www.ams.usda.gov/AMSv1.0/gtfile?dDocName=STELDEV3004376
“Louisiana the Perfect Hot Sauce” Nutritional and diatary information. Date accessed
11/22/2008, www.louisianapepper.com
“Milk of Magnesia” Nutritional Drug information. Date accessed 11/26/2008,
www.medicinenet.com/magnesium_hydroxide-oral/article.htm
“Scope: Oral Mouthwash” Nutrition and Ingredients. Date accessed 12/2/2008,
www.householdproducts.nlm.nih.gov
“Silk Soy Milk”, Nutrition and Information page. Date accessed 12/2/2008,.
www.silksoymilk.com/Products/SilkSoymilkRefrigerated.aspx