Difference between revisions of "Part:BBa K1149051:Experience"

Revision as of 07:57, 30 October 2017

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Applications of BBa_K1149051

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UNIQf582ed5fac3fb870-partinfo-00000000-QINU UNIQf582ed5fac3fb870-partinfo-00000001-QINU The Stanford-Brown 2015 team wanted to build off of the Imperial College team's work by adding the gene for a type II pantothenate kinase (panK) to this part to make a composite part (BBa_K1692021). To test whether the panK gene caused more plastic to be produced, we used this BioBrick as a comparison. Our final results did show that the addition of the panK gene did cause an increase in plastic production, as shown by the figure below.

This plot shows the increase of the percent of dry cell mass that is P(3HB) and the increase in relative fluorescence. The measurements of our construct are in general higher by both of these measurements, which suggests that our construct works successfully.

Notably, we used the strain NEB5-alpha instead of the same strain as the Imperial 2013 team used (MG1655). NEB5-alpha is not known to be a high accumulator of P(3HB), but is is a common strain so we wanted to use it to test our construct. Even though our construct produced, on average, a 23% increase in the amount of plastic in vivo as a percentage of dry cell weight over the Imperial 2013 construct in our lab, we still produced less plastic than the Imperial 2013 did. As opposed to their value of 58.9% plastic, we were only able to achieve 25-34% yield. We suspect that is due to the strain difference, since the media difference should have worked in our favor (we used TB, which the Tokyo Tech iGEM 2012 team had shown causes more plastic to be produced). However, supplementing the media with glucose, as opposed to as with glycerol, could have also caused the difference in accumulation.

Calgary 2017: HPLC of PHB digestion in sulfuric acid

In order to further characterize the part, we carried out digestion of PHB produced from this part and analyzed the amount of crotonic acid produced. The protocol used for digestion is given on our page. The digestion times used were 20 mins (Low) and 30 mins (High). About 0.0249 g of PHB obtained from extraction was used for the experiment. The following figures show the HPLC results obtained.

A standard curve was generated using PHB from Polyferm with known concentration of PHB. The concentrations of PHB used for standard curve were 0.01 mM, 0.25 mM, 0.5 mM, and 0.75 mM. The area of crotonic acid from HPLC results was then used to calculate the concentration of PHB in sample. The standard curve generated is shown below:

The HPLC results showed that crotonic acid was present in the samples with 20 mins and 30 mins of digestion time. Thus, as seen in literature that the presence of crotonic acid is a positive test for confirmation of PHB in sample.