Abner Ramirez's Bacteria Page

The petri dish i had contained nutrient broth agar. It was exposed to the atmosphere in my room for twenty minutes on September 16 at around 9pm. It was then kept undisturbed on a drawer where it would only be moved when taking a picture of the dish to record the growth of the colonies. The temperature in the room was fairly warm(due to the warm weather and no AC) ranging from 75°F-85°F.The petri received minimal exposure to light since little light enters through the window in the room ,due to its position. 

Results 1. Total Number Of Colonies Formed
Data Table 1. Total Number Of Colonies Formed
Day # of colonies formed
Day 0 0
Day 1 5
Day 2 7
Day 3 9
Day 4 10
Day 5 11
Day 6 11
Day 7 11
Day 8 12
Day 9 12
Day 10 12
Day 11 12
Day 12 12
Day 13 12
Day 14 12
Day 15 12

Results 2 Individual Colony Growth
Table 2 Individual Colony Growth
total # of each type of colony
Day yellow black
0 0 0
1 4 1
2 6 2
3 7 2
4 8 2
5 9 2
6 9 2
7 9 2
8 10 2
9 10 2
10 10 2
11 10 2
12 10 2
13 10 2
14 10 2
15 10 2

Although there was only 12 colonies in my petri dish,the bacteria in the nutrient broth agar grew logistically. It grew rapidly the first 5 days, after which it slowed down dramatically ,and leveled out as it approached the carrying capacity, 12 colonies.The colonies were spaced out and did not cover the entire plate. Since the temperature of the room was between 75°F-85°F, which is well within in the temperature range ideal for bacteria growth (41°F-135°F), the exposure to light kept at a minimum, and there was more than plenty of space inside the dish, the only limiting factors were the amount of nutrient broth and the competition for that resource since there were two different types of colonies. The effect of limited resources( the agar) is shown by the first chart. The bacteria grows somewhat rapidly the first few days, and as the agar is being used up, the growth rate slows down until it reaches the carrying capacity, the maximum population that can be sustained by the amount of agar in the dish.The effect of competition and limited nutrients on population growth can also be shown by the distribution of the colonies and by the growth of the black colonies.The black colonies growth was impeded by the yellow colonies and the almost uniform distribution of the colonies show the need to maximize the distance between them and others so that they can get enough of the very limited nutrient broth.Had there been more agar contained within the dish the colonies would've been able to cover the whole thing since the amount of colonies would have increases with the new carrying capacity.

I've learned bacteria grows at a rate that's affected by it's surroundings and resources, and that the concepts of species distribution,logistic population growth, limiting factors, and carrying capacity apply to almost all living things, even ones as small as a single cell microorganism ,such as bacteria.