A) For hundreds or even thousands of years, Yogurt has been a delicious treat enjoyed by humans all over the planet. Yogurt is a food of mysterious origins, and has been an early example of biotechnology. However, the process of yogurt making is very different than one would think. Bacteria plays a major role in yogurt production, thus making it an important topic. Bacteria is the most populous and successful form of life on earth, and has played a large role in human history. Although only a surprising minority of bacteria is known to cause disease, pathogenic bacteria in the form of cholera, typhus, tuberculosis, and the bubonic plague have caused the suffering and death of millions. However, the bacterium that we are to be using for our yogurt is a type that is not harmful towards humans.There are many distinct shapes of bacteria, such as coccus (spherical), bacillus (rod-shaped) and spirillum (spiral). These different types of bacteria reproduce through binary fission, which allows them to divide every 15-20 minutes. The yogurt we shall be producing is a pro-biotic, meaning that it is designed to aid the helpful bacterium which reside in the stomach of humans along the stomach and small intestine.
B) Our purpose for this experiment will be to test Koch's postulate (which has four steps: find microbe present in all sick people, culture the micrrobe, inoculate a healthy subject with the microbe, culture the same microbe from the newly sick), and practice the microbial technique.
C) To make our yogurt, we will scald the milk to 80 degrees Celsius (pasteurize) to kill spoilage bacteria, then we will cool down the milk, add the yogurt and wait for 24 hours. The way this process is completed, is that the milk sugar, lactose, is converted into lactic acid. This decreases the milk protein, casein, and turns the milk from a semi-liquid to a semi-solid. This process is known as curdling.
D) The controls of this experiment will be tube 1, which is the negative control, and tube 2 which is the positive control. The variables of the experiment are tube 3 and tube 6, because tube 3 is indicating the yogurts reaction to ampicillin, and tube 6 is monitoring the growth of E-Coli. My predictions for this experiment are that tube 3 loses the benefits of a pro-biotic, and tube 6 grows into a healthy medium.
