Succession Experiment

Introduction Succession is the measurable process in which a community changes and thus the community as a whole is altered (Friedman 2017). To study succession, one must use one of the following methods: to observe any patterns that occur, to conduct experiments that manipulate specific variables in a community, or to construct a model that may undergo succession. One example of an experiment that measures microbial succession was an experiment observing changes in traditional Chinese soy sauce over time (Sulaiman et al. 2014). The fermentation of the soy sauce brine revealed that the primary bacteria shifted from the bacteria with the genus Weissella to bacteria with the genus Candida over time. This occurred while the pH value steadily
The components of milk also determine the possible bacteria that can grow, which includes water, fat, proteins, lactose, total solids, and minerals (Friedman 2017). The flavor and nutrients stem primarily from the milk fat, proteins, and lactose. When left to sit at room temperature, a cream will form on the surface of whole milk, and a smaller and lower cream will form in skim milk. The cream is partially comprised of solid fats, and the deterioration of these fats may alter the flavor. Caseins, a major protein in milk, can be separated in the aqueous milk environment at room temperature because the bacteria break down the caseins and release acid or renin, which decreases the pH of the solution over time. The cultured milk should have the most microbial succession because of the consumption of the nutrients by bacteria that causes change in the milk environment. The purpose of this experiment is to measure the change or patterns in microbial diversity in the milk samples over
Table 1 displays the five different conditions analyzed over the course of about two weeks (see Appendix). We practiced sterile techniques every time we were in the lab. We made streak plates every three to four days (excluding weekends) a total of five times using the streak plate method explained in Friedman’s lab handout (Friedman 2017). Each day we made streak plates, we plated two nutrient agar plates and two M17 plates. One nutrient agar plate and one M17 plate was stored in a 37℃ environment and the other plates were stored in a room temperature environment. About 24 hours later, the colonies on the plates were counted and the plates were moved to a 4℃ environment to be stored until they were Gram stained using the process outlined in Friedman’s lab handout (Friedman 2017). Liquid cultures were made (from the streak plates stored) every seven days on the day before Gram staining. Observations of the milk samples, including pH, odor, and color, were recorded daily. The liquid cultures and plates were Gram stained every seven days. Observations of the Gram stained samples made under the microscope were