Result of Diacetyl Volatile Test

For the diacetyl volatile test, 6 sets of the tests were performed using different concentrations of diacetyl. Each set was repeated twice to obtain an average responsive index to maximize accuracy. For 1x concentration of diacetyl, the average index was 0.96. At 1/10x concentration, the average index dropped slightly to 0.84. From then on, it dropped dramatically to 0.27 at 1/100x concentration, then to 0.17 at 1/1000x concentration. At 1/10000x concentration, the index was at 0.05. but it rose slightly to 0.06 at 1/100000x concentration.

All the indices collected were positive. This suggests that diacetyl is a volatile attractant. The high index recorded at 1x concentration shows that diacetyl is the most potent attractant. However, as evidenced by data from 1x concentration to 1/1000x concentration, when concentration is lowered, its potency as an attractant decreases. It can be concluded, hence, that the potency of diacetyl as an attractant is directly proportionate to its concentration up till 1/1000x concentration. The slight rise in average index at 1/100000x concentration suggests that 1/100000x diacetyl is a slightly stronger attractant than 1/10000x diacetyl.

As a result, this assay proves that pure diacetyl attracts C. elegans and can be utilized in our experiments with transformed bacteria.

Result of Cinnemaldehyde Volatile Test

For the cinnamaldehyde volatile test, 6 sets of the tests were performed using different concentrations of cinnamaldehyde. Each set was repeated thrice this time. The results were processed to produce an average responsive index. For 1x concentration of cinnamaldehyde, an average index of -0.81 was recorded. The index then fluctuates slightly to -0.8 at 1/10x concentration and to -0.82 at 1/100x concentration subsequently. The index then drops to -0.5 at 1/1000x concentration. The index decreases dramatically to -0.13 at 1/100000x concentration. It finally decreases to -0.1 at 1/10000x concentration.

All the indices collected were negative. This suggests that cinnamaldehyde is a volatile repellant. The similarly high negative indices at 1x concentration to 1/100x concentration show that cinnamaldehyde is a strong repellant. The difference in indices is only 0.01, hence, it suggests that he differing concentrations have little to do with the repelling effect of cinnamaldehyde. The negative indices then decrease along with concentration as evidenced by the data from 1/1000x concentration 1/100000x concentration. This shows that the repelling effect is directly proportionate to the concentration of the cinnamaldehyde.

As a result, the assay proves that pure cinnamaldehyde repels C. elegans and can be used for our experiments.

Result of Phenylpyruvic Acid Droplet Test

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Overall Comparison

As an overall comparison of pure chemicals, the responsive index for diacetyl was 0.96. Chili oil had a lower responsive index of 0.59 while phenylpyruvic acid (PA), had the lowest responsive index of 0.34. Water was used as a negative control and obtained an index of 0.07. This shows all three pure chemicals were attractants with diacetyl being the most potent.

In our experiment, we used transformed bacteria containing the composite part to produce synthetic PA. Its responsive index was 0.83. Comparatively, the responsive index of a transformed bacteria with an empty vector was 0.63. while it is known that bacteria attracts C. elegans as a food source, the data proves that our bacteria indeed has potency as an attractant that is independent of its nature as a food source. Hence, our bacteria are attractants to C. elegans in themselves. The transformed bacteria had a higher index than PA and chili oil, suggesting that the bacteria are stronger attractants. However, the bacteria still have a lower index than diacetyl. It can be deduced that diacetyl is still a stronger attractant than our transformed bacteria.

Comparatively, cinnamaldehyde had -0.81 responsive index. It was the only chemical that had a negative index, suggesting that it is the only repellant in our range of chemicals. It is a strong repellant as evidence with its obtaining a highly negative index.