V. Discussion:
The hypothesis, E. coli k-12 colonies cultured with S. cerevisiae will decrease in growth as indicated by a lower E. coli k-12 colony count for higher levels of S. cerevisiae, was supported by the data from the first experiment. With the 102 dilution factor of S. cerevisiae less E. coli k-12 growth was evident (as this represents the treatment group with the higher level of yeast present) than in the groups plated with a 104 dilution factor (a more diluted culture) and plated with no S. cerevisiae. The null hypothesis, E. coli k-12 colonies cultured with S. cerevisiae will show no difference in growth for higher levels of S. cerevisiae, was rejected. Two-tailed z-tests were used to determine if the difference between the groups’ means were statistically significant and these values showed a significant difference between the E. coli k-12 colony counts of the 102 dilution treatment group and the other two groups plated with E. coli k-12. Thus with higher growth of S, cerevisiae there was lower growth of E. coli k-12. However, statistical data did not report any significant difference between the mean colony counts of E. coli k-12 in the lower level S. cerevisiae treatment group and the Control E. coli k-12 treatment group.
The hypothesis, E. coli k-12 cultured with S. cerevisiae will have a higher rate of agglutination (adhesion) to yeast as indicated by a higher count of E. coli k-12 colonies within 1 mm of S. cerevisiae, was supported by the data from the first experiment. With the higher level of (102 dilution factor) S. cerevisiae plated the number of agglutinated bacteria was higher. The null hypothesis, E. coli k-12 cultured with S. cerevisiae will have no difference in rate of agglutination (adhesion) to yeast, was rejected. A two- tailed z-test was performed and showed a significant increase between the counts of agglutinated bacteria with the increased presence of S. cerevisiae. Furthermore, this same data provided an even more interesting conclusion: the level of yeast necessary is a dose-able factor. The factor was first determined by calculating the Agglutinated Ratio as the number of E. coli k-12 colonies within 1 mm of S, cerevisiae colonies to the total number of S. cerevisiae colonies. This number was found to be quite similar between the two groups at around 1.65. A statistical z-test further supported the inference that the ratios were the same as the data was proven to be statistically similar. Thus if a patient’s relative initial exposure to pathogenic E. coli k-12 is known a physician may prescribe, with some certainty, an appropriate level of S. cerevisiae for probiotic treatment.
The hypothesis, S. cerevisiae cultured on glucose enriched media will have higher colony counts of S. cerevisiae, was supported by the data from the second experiment. Statistical z-tests were also done comparing the mean S. cerevisiae colony counts of all three other treatment groups to the mean S. cerevisiae colony count of the glucose enriched treatment group and this data further supported the hypothesis. The null hypothesis, S. cerevisiae cultured on glucose enriched media will have no difference in colony counts of S. cerevisiae, was rejected as z-tests showed significant difference between the growth of yeast in this group as compared with that of the other plates.
The hypothesis, S. cerevisiae cultured on glucose enriched media will have more probiotic effect against E. coli k-12 indicated by a higher Agglutination Ratio of agglutinated E. coli k-12 colonies to yeast colonies, was supported from data illustrated in the second experiment. Both experimental and statistical analysis supported this hypothesis in showing that there was an increased ratio of agglutinated E. coli k-12 in the glucose enriched media (translating to a glucose enriched diet). This should suggest then in order to maximize efficacy of S. cerevisiae as a probiotic against pathogenic E. coli k-12 one should supplement doses with simple sugars. Holistic data supports this generalization: though there were increases in both S. cerevisiae and E. coli growth only the increase in S. cerevisiae was proven statistically significant upon performing a one-way ANOVA. Furthermore, the agglutinate E. coli ratio was increased from the first experiment to this group. Thus, as a clinical and pharmaceutical application, yeast supplementation products should be advised to be taken with a food source rich in simple sugars as opposed to one rich in fats (or one complexed with both for that matter).
VI. Future Study:
Upon continuation of this research the second experiment – designed to identify a diet supplement that would maximize the efficacy of the yeast as a probiotic (by maximizing the agglutinated numbers of E. coli k-12 while minimizing the total number of E. coli k-12) – would have to be redesigned and retested. Potentially different diet supplements could be tested as well, for example more complex sugars such as lactose and starches, or proteins and vitamins and minerals. Furthermore, to improve this portion of the experiment it would be important to potentially include an in vivo study to better understand the strains the digestive system would put on the interaction between the two microbes. However a study like this would need to incorporate many controls.
To further the applicability of this research, it would be important, to compare S. cerevisiae performance as a probiotic against that of other well established probiotics such as Lactobacillus and S. boulardii (actually a sub-group of the S. cerevisiae species). However, these tests would have to be in vivo as these microbes all have different modes of action as probiotics and thus the only method of comparison would be their effects on the whole of the system.
Finally, though not so related to this current study, much research has been done on S. cerevisiae’s effects as a probiotic in ruminant species. Yeast has been shown to have significant and measurable effects on the balancing and removal of harmful microbial biota in the stomachs of the species as well. It has been shown to counter S. ruminantium, Streptococcus bovis and Salmonella colonies in these animals. Yeast integration by farmers into the diet of beef cattle has shown increases of upwards of 13% of usable beef and a 4% increase in production of milk by supplemented dairy cattle. These statistics are very important in the agriculture and consumers industries and thus should be a point of concern in the scientific community.
