So after we went through the yogurt lab procedure and put all four tubes in a warm bath overnight, what happened?
We collected the tubes and observed the changes that occurred and discovered some pretty interesting information. The control tube of just milk did not turn into yogurt. Obviously there was some spoilage bacteria that cultured overnight because the milk smelled quite sour. The tube with a dollop of yogurt added to it cultured overnight and the entire tube had started to turn into yogurt. This confirms our hypothesis that the yogurt would grow overnight in the tube. However, the tube with E. Coli did not turn into yogurt, proving that not all types of bacteria have the ability to create yogurt. The tube with ampicillin, an antibiotic, did not create yogurt. Because ampicillin killed the bacteria in the milk, there was no way it could culture into yogurt. Overall, we learned that bacteria is able to reproduce very quickly in a favorable environment. A small amount of yogurt added to milk can be cultured into more yogurt if the bacteria are able to reproduce. However, not all types of bacteria cause milk to transform into yogurt, and some types of bacteria cause the milk to spoil. If an antibiotic is added to the milk, it can be preserved in its natural state without spoiling or turning into yogurt. We were careful in our procedure but there are many sources of error that we could have encountered. Factors like not adding the correct amount of an ingredient, using any tools that were not sterile, or not putting the caps on the tubes correctly could have greatly affected our results.
