The air, equipment, benches, and surfaces of the laboratory are laden with microorganisms. The microorganisms may be either harmless or rogue. An example of a harmless microorganism includes the normal flora which do not contaminate the experimental results. Rogue microorganisms contaminate the laboratory experiment which leads to inconclusive findings. The success of a microbiological experiment is therefore dependent on the effectiveness of the aseptic or inoculation technique. The aseptic technique is defined as a procedure which employs sterile conditions to perform procedures (Talaro & Chess, 2007). The aseptic techniques include laboratory and medical techniques that involve human cells and culture media. Culture media include the substance which is necessary for the development of microorganisms outside the body. In this experiment, the processes used in the inoculation of culture media are undertaken to determine their effectiveness.
Materials and Procedures
The materials utilized in this experiment include a Bunsen burner, 4 Petri dishes, 1 rack, 1 inoculating loop, 8 tubes, nutrient agar slant cultures (24 hours), and nutrient broth (24 hours).
I labeled the tube to be inoculated with the organism’s name and my initials.
I held the tube to be inoculated and the stock culture tube such that the two tubes almost formed a V in my palm.
I then took the inoculating loop and put it over the hottest part of the Bunsen burner’s flame in order to sterilize it. I ensured the loop, including its handle, was red hot. I then held the loop on my hand for about 30 seconds until it cooled down.
I then uncapped the tubes by lifting the closure upwards and then kept it in my palm with the inner part of the caps facing upwards. This ensured that I did not contaminate the caps by placing them on the working bench.
I then passed the mouth and necks of the tubes over the Bunsen burner’s flame rapidly for several times and allowed them to cool.
For the inoculation, I took the inoculating loop and used it to touch the surface of the inoculum solid medium from the agar slant carefully at an area which exhibited growth. I did this carefully to avoid gouging the agar.
I then shook the inoculating loop lightly on the broth culture and thereby dislodging the microorganisms.
I then re-flamed the tube necks after withdrawing the inoculating loop. I then replaced the caps cautiously in a way that each cap went back to its original tube.
Afterwards, I put the inoculating loop over the Bunsen burner’s flame and ensured that it turned red hot for the purpose of destroying the remaining microorganisms.
I then transferred the bacterium’s broth culture and the bacterium’s agar slant to a nutrient broth and nutrient agar slant separately.
I finally incubated the cultures at 25 degrees Celsius for 24 hours.
Positive growth that was seen in the nutrient broth tube and the nutrient agar slant tube indicates that the organism was able to develop inside these tubes. The growth of the organism in the two tubes indicates the presence of an environment that favored their growth. Such factors include the optimal incubation temperature and pH. However, the most important reason that encouraged the growth of the organism is the absence of external microorganisms that could discourage their growth. This shows that the inoculation of the tubes and the transfer of the organism was successful and effective.
Through the successful growth of the organism in the nutrient broth and nutrient agar tubes after the transfer, the experiment shows that the aseptic technique was carried out properly. Most importantly, the inoculation of the culture media and transfer of the organism was successful.
- Talaro, K., & Chess, B. (2007). Foundations in microbiology (6th ed.). New York, NY.: McGraw-Hill Education.