Lawrence Kim's Bacteria Page

I exposed my petri dish to the atmosphere in my bedroom for 10 minutes. The bacteria in my petri dish is M.M (minimal medium). The temperature in my room is relatively hot during the day because my apartment builds up heat from the bottom. During the night, the room cools down a lot. I left the petri dish on my desk in my room in the same spot. It is not exposed to sunlight at all and experiences periods of condensation on the top of the lid.

Bacteria Growth Experiment

Result #1: Total Number of Colonies

Total Amount of Colonies Over 15 Days

Result #2: Area of Colonies

Area of Colonies


        I exposed my petri dish in my room for 10 minutes every day.  From about day 3 to day 28, the number of colonies kept increasing and decreasing. I think the new colonies kept forming, but some died off due to lack of resources. I saw that position played a key role in the survival of colonies because colonies that grew near each other were more likely to survive for a longer time than the isolated colonies. Also after day 28, the colonies slowly started to increase steadily.

    Each colony did not surpass an area of 1.5 mm. They all stayed relatively small and a few vanished. In addition, the colonies were (for the most part) together. I think that my colonies had a carrying capacity, but it was not reached due to the lack of time. If i continued my experiment for one more month, I hypothesize that the colonies would reach the carrying capacity. I also believe that due to fact that the colonies were clumped together, less nutrients were absorbed for each colony. Thus, leading to my reason explaining the colonies needed a better surrounding area with nutrients instead of competing colonies to grow larger. 

What I've Learned: 

    During this experiment, I have learned that bacteria and fungi do compete for nutrients. Although on a micro scale, competition for nutrients affects the individual's growth and health. I have witnessed that carrying capacity can threaten the downfall of individuals who lack the strength to stay alive. The petri dish and growing bacteria limited the area for colonies to grow, therefore it led to competition. With more nutrients and colonies spread apart, each colony could grow to become much larger.