6 thoughts on “D1c – Roeder

  1. Great job! Is it possible to explain more on tea tree oil, I may have misheard some information or didn’t hear when you explained the purpose of it in your presentation!

    1. Tea tree oil has been used as an antimicrobial for a long time. Research on tea tree oil in the past has found that there are a number of active compounds, but terpinen-4-ol is the most prominent one. Specifically, the previous research showed that terpinen-4-ol weakened the bacterial membrane. That is why we choose to study it.

    1. Ethanol kills bacteria. It is what we use in the lab to kill any Salmonella that may have gotten on to the bench while we were working. However, the concentration of ethanol normally has to be at about 90% or higher for it to be effective in killing the bacteria. With 70% ethanol, the majority of the bacteria should have survived, so the 70% ethanol we used as our negative was much more effective in killing the bacteria than it should have been. This could have had something to do with the specific strains of Salmonella we were using being more susceptible to ethanol, but we did not look into it.

  2. Was the tea tree oil compound only effective at low concentrations and not at higher concentrations? I’m not sure I understood this part correctly, but if so, why do you think it only worked at lower concentrations?

    1. It was more effective at high concentrations than at low concentrations. The graphs show compound identity on the x-axis and absorbance in the spectrophotometer on the y-axis. The bacteria are what absorbs the light, so higher absorbance indicates more bacteria. This means that a lower absorbance, or a shorter bar on the graph, indicates a more effective drug because there is less bacteria. The 10% terpinen-4-ol concentration on the first graph and the 3%, 2.5% (blue bar), and 2% concentrations on the third graph were very effective at inhibiting the bacterial growth because the absorbance was low, which means there was a low amount of bacteria. At the lower terpinen-4-ol concentrations on the third graph, the absorbance started to rise, which indicates that the effectiveness was decreasing.

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