Bacteria Lab Write Up

1. Question: Which source of bacteria grows the fastest?2. Hypothesis: The bacteria source from the trash can will grow the fastest.3. Procedure:

1. Have a petri dish with agar on the bottom and separated into 6 different triangles. Label them A, B, C, D, E, and F. Keep C clean for the controlled variable.

2. Take a metal stick that is curved at the end and put it upon a fire to get rid of all other bacteria on it.

3. Take the now clean metal stick and rub it across a surface.4. Take the now contaminated stick and lightly rub it on a triangle

on the petri dish. Do this five more times on all the other triangles.

5. Close lid so that airborne bacteria will not land on the bacteria inside the petri dish.

6. Check its daily growth. Record its color/texture, # of colonies, the measurement, and whether it has fungus or not. Repeat for next six days.

4. Data Tables

a. Petri Dish

Sales

Section ASection BSection CSection DSection ESection F

b. Daily Entry of Observations

<- Day 1.Day 1

Measurement in millimeters:

# of colonie

s:

Color/Texture: Fungus/No

Fungus:A. 6 2 Streak of white NoB. 1 3 2 shiny white dots NoC. 7 1 Hairy, shiny yellow dots YesD. 1 2 2 white dots YesE. 3 2 1 yellow dot NoF. 1 45 Brown hairy circle shape Yes

<- Day 2Day

2Measureme

nt:# of

colonies:Color/Texture: Fungus/No

FungusA. 8 107 Streak of white dots NoB. 2 5 3 shiny white dots NoC. 1 3 Brown, hairy, pink dot in

middleYes

D. 2 2 2 white dots YesE. 4 4 Big yellow dot, 2 small

white/yellowNo

F. 11 47 Fuzzy, brown circular Yes

<- Day 3Day

3Measureme

nt:# of

colonies:

Color/texture: Fungus/No Fungus:

A. 12 174 Streaked with white dots NoB. 2 6 Small dots, pastel colored NoC. 2 3 Brown, fuzzy circles YesD. 3 2 Brown fuzzy with white

dotsYes

E. 5 4 Yellow, gray, white dots NoF. 14 47 Brown fuzzy dots No

<- Day 4Day

4Measuremen

t:# of

colonies:Color/texture: Fungus/

No Fungus:

A. 14 181 Streaks of white spots NoB. 2 6 Yellow, white, orange dots NoC. 16 5 Brown, fuzzy, grouped YesD. 10 3 Pastel colored dots YesE. 4 4 2 orange 1 cream 1 coral NoF. 16 52 Bigger, brown, fuzzy Yes

<- Day 5Day

5Measureme

nt:# of

colonies:

Color/texture: Fungus/no

fungus:A. 10 197 White streaks, more visible NoB. 3 8 Orange, yellow, gray dots NoC. 27 5 Big, brown, fuzzy, with one 1

dotYes

D. 13 3 Fuzzy with 2 cream dots YesE. 4 4 2 orange 1 cream 1 coral dots NoF. 16 54 Fuzzy, brown/black Yes

<- Day 6Day 6

Measurement:

# of colonie

s:

Color/texture: Fungus/No

fungus:A. 14 204 Streaks of white NoB. 4 7 Orange, yellow, gray dots YesC. 3 4 Big, brown fuzzy circle YesD. 4 3 Brown with 2 cream dots YesE. 5 4 2 orange 1 cream 1 coral dots NoF. 18 59 Fuzzy, brown overlapping Yes

Graphs

Graph 1: Measurement & # of colonies VS Time

Day 1 Day 2 Day 3 Day 4 Day 5 Day 60

0.5

1

1.5

2

2.5

3

3.5

# of coloniesMeasurementColumn1

Graph 2: Number of Colonies VS Colors

White Orange Yellow Gray0

10

20

30

40

50

60

Section ASection BSection CSection DSection ESection F

Graph 3: Colonies VS Colors on Last Day

White Orange Yellow Coral0

10

20

30

40

50

60

Section 1Section 2Section 3Section 4Section 5Section 6

Analysis

The first day of this experiment, we saw that section F had grown the most over the span of 3 days. The brown fungus had grown very fast compared to any of the other sections that had yet to grow much. Sections A, B, and D had no distinct fungus or bacteria. Sections C, E, and F did. Section C was supposed to not have anything on it, but a fungus had start to grown. We guessed it was an airborne bacteria that had fallen on our open petri dish. Section E had a distinct yellow dot. Section F had grown many brown fungi. Throughout the 6 days, Section A had started to show up in streaks of white dots. Sections A, B, and D had grown pastel colored dots. Section F grew darker and started to overlap each other.

The fungi were brown and fuzzy. It looked hairy and if you lifted it up to the light, you could see small hairs. They were shaped in circles and usually overlapped each other if there were a lot. The fungi grew very close to each other if there were more than one. The bacteria were not too big. They were usually brightly colored, like orange or yellow. They usually were not too close to each other. Some grew on the sides of the dish, but most grew where the agar was.

From all 5 sources, the bacteria from the fish tank had grown the fastest in the shortest amount of time. In just 3 days, the fungi had swarmed the whole section that it was in. The bacteria from behind

Ashley’s ear had grown the most consistently in the span of 6 days. The bacteria from Collin’s hair had grown the least, but there were big white dots. The bacteria from the trash can and the knob of the girl’s bathroom stall had grown around the same amount in the span of six days. They only had a few spots.

The bacteria and fungi had grown because of the food it had under it, which was the agar. Whichever source had the most bacteria grew more than other sources that had less. Because of the agar, which was its food, it had grown consistently until it had reached its carrying capacity. That was when it had grown the most it could and could not grow anymore. By keeping the lid closed the petri dish, airborne germs could not reach the bacteria inside the petri dish.

Conclusion

My question was which source of bacteria grows the fastest? I answered it with my hypothesis that the bacteria from the trash can will grow the fastest. My hypothesis was wrong because it grew slower compared to the bacteria from Ashley’s ear or the bacteria from the fish tank. My proof is that the bacteria from Section F grew thicker and thicker as the days went by. It was the same for the bacteria in Section A. The bacteria from the trash can grew about 6 spots in 6 days. The bacteria from Sections A and F grew many spots in just 3 days.