Overview

In order to meet the requirements of iGEM, models of our projects are dedicated to solving the problems in experiment and providing guidance for the products. Our project is mainly based on bacteriostasis and incense production, while PLA is the major bacteriostatic material, so we have built two models about mechanism and yield of PLA with innovation and practicability of development as the following.The first model is about Mechanism of PLA .The second model is about PLA yield curve. The result of our models has a application.

Mechanism of PLA

Effect of different concentration of PLA on the number of Staphylococcus epidermidis.

Introduce
we had planned to established a dynamic equation to describe the effect of PLA on staphylococcus epidermidis which is the main bacteria that cause the armpit order. We gave several candidate forms of function for describing this process and finally found the best one which fit the experimental data quite well. By using the data from the experiment，we continually refine our models and guide our project through this models. Besides, this model, of which type has never been built before, also makes us learning the mechanism of PLA and solved problems as following:
(1) How many PLA should we put in our products that can kill the desired amount of staphylococcus epidermidis?
(2) What is the effect of concentration of PLA on the number of staphylococcus epidermidisover time.
（3）What is the growth of bacteria at any concentration of PLA?

Method
To solve the problems above, we used different concentration of PLA to react with Staphylococcus epidermidis, then we measured the rest of bacteria every hour for a total of 8 hours. Through fitting the initial data, we got the following chary and found the appropriate function to describe this figure.

Machine
Molecular Devices SpectraMax i3x

Methods

  We followed this protocol to do the Interlab Study.
  When we completed three of the calibration measurements, performing the cell measurements. Used the same plates, volumes and settings that we used in calibration protocol. We transformed E.coli DH5α competent cells with the 8 plasmids and picked 2 colonies from each of plates into 5 mL LB medium + Chloramphenicol. After culturing the cells overnight at 37°C and 220 rpm, we used plate reader to measure the Abs600 and fluorescence of samples at 0, 6 hours.

Result

Calibration
Calibration 1: OD600 reference point

Calibration 2: Particle Standard Curve

Cell measurement

Analyse

  A standard curve in a linear relationship can be obtained by calibration experiments.
By comparing and analyzing the fluorescence values and Absorbance value of the different test devices at 0 and 6 hours, we can draw the following conclusions: the negative control and the positive control showed significant differences in the 6h fluorescence measurement results. Among the six different test equipment, Device 4 has the strongest fluorescence, while Device 3 has the lowest fluorescence. Compared with the relation between absorbance and fluorescence value, we can't get the relationship, and we need to improve on the control variables during the experiment.

Summary

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