Bacteria Lab experiment

Purpose: to explore the growth og bacteria and the effect of the following treatments

              -disinfectant

              -soap(no mechanical rubbing)

-The bacteria will be from: a) know sample: Sarcina aurantiaca (latin name)

                                           b) 3 unknown samples from around PW and 1 from the scotch tape

        

-Aseptic technique: Uses the bunsen burner to sterilized both the loop and the mouth of the know sample test tube to avoid cross-contamination  from the microbes.

-Record observations using drawing or camera

Materials: -3 plates of nutriet agar

                -1 paper disc soaked in LYSOL

                -scotch tape

                -1 control paper disc  

                -1 streile paaper disc

Procedure:

-Known sample
1. use the aseptic technique and place some known sample in one of the agar plates

2. seal the agar plate with known sample with tapes and label it
4. wait for the bacteria to grow.
5. record observations

-Known sample with discs (use the above plate if a third plate is not available)
1.Divide a plate into four sections - E,F,G,H
2. use aseptic technique to place some known sample on the plate
3.place the soaped disc in section E, Lysol disc in  F, control disc in  G and sterilized disc in H
4. wait for the bacteria to grow.
5. record observations

-Unknown samples
1.label and divide an agar plate into sector A,B,C,D equally

2. search for 3 unknow samples around PW by scotch tape and place them in 3 of the 4 sectors on
the plate. The fourth sample is the tape itself and acts as a control sample. Place it on  the fourth sector.
(Sector A:stair rail/ Sector B: door push/ Sector C: door knob/ Sector D: control sample of the tape)

3.label the sample to indicate the origin of the samples after sealing the plate

4.Wait for the bacterium to grow.

5.record observations

First Observation:

-Known sample plate: on the sector E (contains soaped disc) of our known sample EFGH plate,  an orange/yellow spot is formed to the left hand side of the sector. This indicates that a single colony is formed by one kind of bacterium. The other four sectors (F,G,H) do not appear to have any formation of bacterial colony. Therefore, they have nil results. Our results appear to be similar to other groups

-Unknown sample plate: a single colony of bacterium is  formed in the sector C which contains unknown sample from a door knob. the colony appears to be in orange and yellowish in which the colour is similar to the known sample. Other sectors (A,B,D) do not appear to have any colonies of bacterium, therefore, they have nil results. However, the stair rail sample of another group appears to be bacterium positive and a single colony is formed.

Second Observation:

-Know sample plate: the result from the second observation is frightening. Before, there was only a single colony formed in sector E. Now, there are yellowish and orange colonies formed all over the plate, some separated, others sticking together. . This result indicates that the growth of bacteria accelerated a lot over the last weekend.

-Unknown sample plate: in sector C, the single colony remains at the same spot and becomes larger in circumference comparing to the first observation. A new single colony is founded between sector A and B which its origin is really confusing. I guess it is from the the stair rail since the chance of getting a bacteria from it is higher.



Conclusion: Although disinfectant and soap are effective for a period of time, they could not kill all of the bacterium. Therefore, two weeks after the experiment, colonies of Sarcina aurantiaca are formed all over the know sample plate and even paper discs 

Photos taken while carrying out the experiment