4. Discussion

Key findings
Based on the findings of our research, we have concluded that Sodium Hypochlorite is the most effective disinfectant agent at lysing E. coli and that Hydrogen Peroxide is the most effective disinfectant agent at lysing S. aureus.

Explanation of key findings
The findings of the research can be explained by the chemical bonds and structure of the disinfectant used. In the case of Hydrogen Peroxide, It releases nascent oxygen which is highly reactive. Its combines with and oxidises the bacteria, lysing it, accounting for favourable results with both bacteria. With Sodium Hypochlorite on the other hand, the dissociation of the Sodium Hypochlorite into sodium chloride and sodium chlorate made the Sodium Hypochlorite into a very strong oxidation agent, which explains the strong results in both cases of bacteria.

Evaluation of hypothesis
Our hypothesis, “Chlorhexidine Gluconate, will lyse the most amount of bacteria for both E. coli and S. aureus” was proven untrue. According to the data collected, Chlorhexidine Gluconate only lysed 14.3 mm and 19.7 mm of E.coli and S.aureus respectively while Sodium Hypochlorite, lysed 19.7 mm of E.coli and Hydrogen Peroxide lysed 33.7 mm of S.aureus. This proves our hypothesis wrong. However, our hypothesis was flawed as there was no mention of what bacteria Chlorhexidine Gluconate was most effective against in the hypothesis.

Areas for improvement

We should have carried out the experiment in a sterile place and environment such as a laminar flow cabinet. The environment of the place we have carried out the experiment, an engineering laboratory, is not sterile. The area we have used to conduct the experiment was simply sterilised with 70% Ethanol. Also, with the presence of other people in the lab, our petri dishes and bacterial cultures may be contaminated.

We should also have sterilised out equipment thoroughly before use. We are not certain if the forceps are sterilised effectively as we had taken them out of the glass bead steriliser after 5 seconds to prevent the forceps from heating up too much, and we placed them on on a platform, tip in the air to cool them down.

The fans were also switched on for the duration of the experiment. That might result in other foreign debris dropping into and contaminating the bacteria culture, even with us utilising the aseptic technique.

Also, the application of the Chlorhexidine Gluconate in the experiment may be flawed. The form in which the Chlorhexidine Gluconate came in was in the form of a thick, syrupy soap. We should have diluted it in sterile water before applying it to the diffusion disks. Without doing so, the Chlorhexidine may indeed be the most effective disinfectant but may not appear so in the application of the Kirby-Bauer method in our experiment as it was too thick, preventing diffusion and lowering the zone of inhibition or lawn clearance of the results.

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