Abstract
In the process of agar preparation, the agar powder was used along with the distilled water. Both were poured together in big flask and mixed well. Then, the flask was put in autoclave machine for sterilization with loosely closed stopper. After autoclaving, the solution was transferred to the Petri dishes. Then, petri dishes were put in incubator. The gram staining was performed next to the process of autoclaving.
Introduction
The experiments were performed for the growth of the bacteria and classification of bacteria. Two major experiments were performed in the lab. The first one was the preparation of agar, which was used for the cultivation of bacteria. When the agar solution in the petri dishes solidified in the incubator at the temperature 37° C, many bacteria samples were swabbed from different area to perform Gram staining. Gram staining was the second experiment, which was performed for the classification of bacteria using microscope. There were two results of the process of Gram staining: Gram-positive and Gram-negative. Gram-positive meant bacteria were present and Gram-negative meant no bacteria in the sample.
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Methodology
Firstly, the 100 ml distilled water and 5.2 gm agar powder were taken in a beaker and in a plate Then, the agar powder, was poured in a big flask along with the 75 ml distilled water and the magnetic needle. The flask was put on the analytical balance until the solution mixed well. Then, flask was sterilized for 10 minutes in the autoclave machine with loosely closed cap at the temperature of 121° C and at the pressure of 15 PSI. Once the pressure dropped down, the solution of the flask taken out of the autoclave and the machine was drained. Then, the agar solution was transferred into the petri dishes and the petri dishes were put in incubator at the temperature of 37° C. When the solution froze in the petri dishes, the samples from different area were swabbed and it was put in incubator to solidify. After some days, when bacteria grew in the petri dishes, the gram staining was performed, and the bacteria was visible in the microscope.
- The bacteria are classified into two major classification by the nature of the cell walls and by the shape. Gram staining is performed for the classification of bacteria by the cell wall.
- General characteristics of prokaryotes: Prokaryotes are shaped as cocci, bacilli and spirals. The cell wall of prokaryote act as an extra layer of protection as well as helps a cell to maintain its shape and prevents dehydration. Many bacteria move using flagellum. Flagellum is long, corkscrew-like appendage and it can protrude from the bacterium surface. The flagella rotate in a clockwise or counterclockwise. clockwise rotation of flagella can change the direction of bacteria (Weibel 2010).
Gram staining is the process of bacteria classification by cell wall. Gram staining was performed on the basis of differential staining with a crystal violet-iodine complex and a safranin counterstain. There were two types of gram bacteria: Gram-positive and Gram-negative. The Gram-negative bacteria were in stains red/ pink color, whereas Gram-positive bacteria were violet in color.
Results
When the agar solution froze in the petri dishes, bacteria samples were taken from keyboard, marker, toilet, door-knob and cell phone. Then, petri dishes were put in the incubator for the bacteria growth. After some days, when bacteria grew the most in all the samples, Gram staining was performed. It was observed that the keyboard, toilet, cell phone and door knob had the most bacteria growth. The bacteria growth of marker was the least.
Discussion
The preparation of agar and the Gram staining process were about the growth of the bacteria and the classification of the bacteria. There were a few precautions that need to be taken in that lab work: the tare button was pressed every time along with the pan on the balance to avoid zero error before adding agar powder. The pan was rinsed with distilled water and the solution was mixed well to maintain the concentration of the solution. The pressure and temperature of the autoclave were the most crucial matter to make agar medium and it was maintained. Bacteria from some areas were not swabbed precisely, which could make an error in the results. The experiment should have been done more than one time for those. The experiment was not carried out with an error because the variations in the gram staining could change Gram-positive bacteria to the Gram-negative bacteria. (GROUP1IBG102 n.d.)
Reference
- Doug Weibel, 2010: https://grow.cals.wisc.edu/deprecated/health/how-bacteria-move
- BY GROUP1IBG102:https://group1ibg102.wordpress.com/2016/10/28/60/
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