Sabrina's Bacteria&Fungi Page

Bacteria Growth


The petri dish was kept on my desk in my room. It was next to a window where there was some sunlight. The temperature remained about 70-75 degrees Fahrenheit although it did reach around 80 degrees Fahrenheit. On the first day, the petri rich was exposed for about 10 minutes and then everyday after that it was exposed for a about a minute at around 8:00pm.

Results
1. Area of Dish Covered by Bacteria

Table 1.Percent of Petri Dish Covered by Bacteria
 Days Percentage of Petri Dish Covered by Bacteria
 1 0
 2 0
 3 0
 4 9.68
 5 14.57
 6 15.85
 7 17.57
 8 24.78
 9 33.82
 10 35.65
 11 36.44
 12 40.27
 13 42.27
 14 44.22
 15 52.14

Graph of Table 1.


2. Individual Colony Growth
Table 2.Growth of Individual Colonies
 Days Type 1
(green)
 Type 2
(yellow)
 Type 3
(black)
 Type 4
(white)
 Type 5
(brown)
 1 0 0     0 0 0
 2 0 0 0 0 0
 3 0 0 0 0 0
 4 2 2 0 1 0
 5 1 1 0 21
 6 1 1 1 11
 7 1 1 1 11
 8 1 1 1 31
 9 1 1 2 21
 10 1 1 2 21
 11 1 1 2 21
 12 1 0 211
 13 5 0 21
1
 14 8 0 1 11
 15 32 0 1 11
Graph of Table 2.

Conclusion
    My graph is an example of logistic growth. The bacteria grew rapidly with in the first 4 to 5 days and everyday after that, it continued to grow, but at a much slower pace. It is likely that there was a limited amount of resources and nutrients and it had reached its carrying capacity, which also explains why the bacteria did not cover the entire petri dish. The first way I collected my results was by calculating the area of the dish covered by bacteria. I first found the area of the each petri dish using imagej and then I found the area of the bacteria covering the plate, then divided the amount covered over the total are to find the percent covered. For the first few days, there was no coverage and on the fourth day it grew rapidly and continue to grow at a steady pace for the rest of the days. My petri dish was approximately halfway covered with bacteria. My second collection method was to count the types of colonies that were growing in the dish. In the beginning, there were more colonies and they were much more colorful but as time went on, they began to merge and one colony (the white one) ended up taking over all of the other ones. Overall, I didn't have very many colonies. 

What I Learned
   I learned many things from this project. I learned about logistic growth and how it can occur not only with animals but on a smaller  level, like with this bacteria, as well. I also learned about carrying capacity and how when a population runs out of resources, the growth rate slows down rapidly. Something else I noticed was that different kinds of bacteria can grow in the same environment.
   
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