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11 thoughts on “D78 – DelReal”
What tests did you do specifically to bring the ethanol percentage down?
We diluted the ethanol with water and did a series of tests with just the ethanol and salmonella compared to Ampicillin control and Salmonella by itself and incubated to watch growth levels. When we deemed it was fairly similar to the salmonella growth on its own, we determined it wasn’t killing the bacteria and would be safe to use to extract our compound.
In your presentation, you speak on how the 30% ethanol was used as your negative control, and you used Ampicillin as your positive control. Could you elaborate as to why you used 30% ethanol as your negative and Ampicillin as your positive?
Our compound was oil based meaning it was not soluble water, it needed to be extracted by means of ethanol. Problem being that 70% ethanol was strong enough to kill the bacteria which would give us false results so we needed a concentration of ethanol that was able to extract the terpinene-4-ol while not killing the salmonella. We used the 30% comparatively as our negative control because it theoretically would show regular salmonella growth, this would determine if our compound was working when we read absorbance levels to see how much bacteria was in each well. Ampicillin was used as a positive control because we know it is going to kill the salmonella, this would give us a frame of reference to determine the effectivity of our compound as an antibiotic.
In your presentation, you talked about how you used 30% ethanol as a negative control and Ampicillin as a positive control. Can you elaborate as to why each was specifically used in your experiment?
Was the tea-tree oil where the Terpinen-4-ol was isolated from purchased at a local grocery store? Do you think different brands of tea-tree oil might change your results?
Luckily we were able to get our hands on the exact compound of 97% terpinen-4-ol so we didn’t have to go through tea-tree oil to extract it, but tea tree oil is what lead us to this compound as it is one of it’s main active ingredients. If we had used tea tree oil from the start we may have seen different results as it has many antimicrobial properties.
What concentrations of ethanol did you test at when trying to find the optimal amount of ethanol to not kill S. Typhimurium?
We started with standard 70% ethanol and did a dilution series to get concentrations of 50% and then 30%. This wasn’t too difficult as 30% seemed to be the lowest we could go while still being able to successfully extract the terpinen-4-ol, so we tested it by itself with the salmonella to ensure it wouldn’t kill the bacteria and that became the standard ethanol concentration for our purposes.
Do you think Terpinen-4-ol would act any different on gram positive bacteria? Is it possible it would suppress gram positive bacteria even more?
This is difficult to say without further testing. Salmonella Typhimurium is a gram-negative bacteria, meaning it does not possess a thick peptidoglycan layer in it’s membrane. That being said results could vary in effectiveness, but our results with gram negative salmonella proved to be bactericidal and killed the bacteria. This would require tests on different cultures, but I definitely believe in the capabilities of Terpinen-4-ol to be effective in many scenarios.