Oral Microbiome
Question: Which sugar (artificial or natural) is going to lower the pH to prevent streptococcus mutans and lactobacilli?
Streptococcus mutans has been identified as an important agent in dental caries. In the microbiome, bacteria interact with each other as they attempt to establish themselves in this environment. (Kuramitsu, 2005). A dynamic relation between sugars and dental caries exists. Sugars and other carbohydrates, after being hydrolyzed by salivary amylase, provide substrate for oral bacteria, which in turn lowers plaque and salivary pH. The result of this action is the beginning of tooth demineralization. Dietary factors such as sugarless chewing gum—especially those containing xylitol, and consumption of sugars in meals as opposed to in between meals may reduce the risk of caries. Low pH in the microbiome favors the growth of the acidogenic bacteria, such as streptococcus mutans. In contrast, a diet low in added sugars and carbohydrates and high in calcium may favor remineralization (Touger-Decker, 2003).
Hypothesis: Comparing artificial sugars to natural sugars, natural sugars will result in the increase of pH, which will decrease Streptococcus mutans and Lactobacilli.
Prediction: Natural sugars will increase the pH, which will lead to an increase in zone of inhibition. The higher the pH, the larger the zone of inhibition.
Experimental Design:
1. Take two petri dishes, one for streptococcus mutans and the other for lactobacilli.
2. Label the dishes (one for streptococcus mutans and the other for lactobacilli.)
3. Plate 200ul of specified bacteria to each of the dishes.
4. Spread the bacteria equally throughout the dish with a T shaped spreader
5. Steralize t
6. Create a positive control disk with bleach and add this to both dishes
7. Create a negative control disk with water and add this to both dishes
8. Measure 4 Tbsp of deionized water in a beaker set to room temperature.
9. Mix 1tbps of cane sugar with the warmed water. The natural and artificial sugars are the independent variables.
10. Submerge two disks in the mixture for 30 seconds
11. Add one disk to each petri dish
12. Repeat steps 5-8 with honey and aspartame
13. Seal petri dishes with paraffin wax
14. Incubate at 37 degrees for one week
15. Measure the diameter of the zone inhibition. The zone of inhibition is the dependent variable.
16. Repeat for a total of 4 trials
Data:
Average Zone of Inhibition in Lactobacilli and Streptococcus Mutans
Week 1
Week 2
Week 3
Week 4
Red Plate
White Plate
Red Plate
White Plate
Red Plate
White Plate
Red Plate
White Plate
Cane
Sugar
0
0
0
0
0.333
0
0
0
Aspartame
2.4
1.86
2.66
2.3
1.76
1.86
1.64
1.56
Honey
0
0
0
0
0
0
0
0
Bleach
0
0
0
0
0
0
0
0
Water
0
0
0
0
0
0
0
0
Std.
dev
0.96
0.744
1.064
0.92
0.68298744
0.744
0.656
0.624
SEM
0.42932505
0.33272692
0.47583527
0.41143651
0.30544127
0.33272692
0.29337212
0.27906128
+/-
2SEM
0.8414771
0.65214475
0.93263712
0.80641556
0.59866488
0.65214475
0.57500935
0.54696012
Conclusio...
