Micro Worksheet

Experiment 6: Microbial Cultivation
Objectives: To successfully cultivate microorganisms from different sources to medium.
Materials: Broth, Agar, Sterilized cotton swab,
Procedure:
1) Get your broth with cotton swab inside containing your bacteria. 2) Remove the cotton and flame sterilize the mouth of the testtube. 3) Get your cotton swab inside, flame sterilize again the mouth of the testtube then plug it with cotton. 4) Grab the inverted plated media and flame sterilize the mouth. 5) Do a multiple streaking in the plated media with your cotton swab. 6) After streaking, flame sterilize again the mouth of the petri dish and then invert it. 7) Throw the cotton swab in a plastic with diluted Lysol.
Results and Observation:
Broth:

Source: Toilet bowl (girls) Source: MCR-PRS lab doorknob
Growth Patters: Growth layered Growth Patterns: Growth layered below surface; none beneath below surface; none beneath center. center.

Plated media: Source: Toilet bowl (girls) Source: MCR-PRS lab doorknob
Colony characteristics: Punctiform; Colony Characteristics: Punctiform;
Raised; Erose Flat; Filamentous

Post-lab Questions: 1) Define a) Flocculent b) Pellicle c) Sediment d) Bacterial Colony 2) What are some signs of growth in a liquid medium? 3) In the streak plate techniques, how are microorganisms diluted and spread out to form individual colony? 4) Which area of the streak plate will contain the greatest amount of growth? The least amount? Explain. 5) Why is it important to invert the plate during incubation? 6) In all routine lab work, Petri plates are labeled on the bottom. Why?

Answers: 1) Definition a) Flocculent- Containing numerous shreds or fluffy particles of grayish or white mucus or other material. b) Pellicle- A thin skin or film, such as an organic membrane or liquid film. c) Sediment- Material that settles to the bottom of a liquid d) Bacterial Colony- a visible cluster of bacteria growing on the surface of or within a solid medium, presumably cultured from a single cell

2) Cloudiness of the liquid is the biggest one I can think of. You can also see color changes (depending on the medium), clumps in side or on top of the medium or a thin haze on the top of the medium. It all depends on what organism you are growing, and what kind of conditions it prefers.

3) Bacterial mixture is transferred to the edge of an agar plate with an inoculating loop and then streaked out in one of several patterns. At some point, individual cells will be removed from the loop and will give rise to separate colonies.

4) It will grow most at the streak from the first sector because the bacteria from the cotton swab is freshly harvested from the liquid broth which contains the bacteria and least is the streak from the third sector because the amount of bacteria in the cotton swab is lesser compared to the bacteria that we swabbed from the first and second sector.

5) This is to stop condensation from forming on the top of the lid. Condensation causes two problems (1) It will allow contamination to enter into the dish by moving accross the water film from the outside (2) It can create a tight seal and prevent oxygen entering the petri dish making it go anerobic.

6) In order to preserve area to observe the plate after it has incubated, write close to the edge of the bottom of the plate.