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One of the more challenging parts of this project. Creating a carrier for our bacteria which is safe enough for normal usage.
Team:Groningen/Template/MODULE/Notebook/Bandage
From 2014.igem.org
Notebook
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The Bandage
June 30 - July 4
Freeze drying L. lactis strain NZ9800 and NZ9700
These cells were stored at -80 °C
July 7 - July 11
Growing an over night culture of the freeze dried
The cells grew on the plate, meaning that L. lactis is able to survive the freeze drying
July 21- July 25
Growing a new overnight cultures and preparing the chemicals for the first polyacrylamide gels with L. lactis cells
Pouring a polyacrylamide hydrogel with Lactococcus lactis NZ9700 in it
Four polyacrylamide gels with different concentration were poured, one of 10 %, 15 %, 20 %, 25 %, and 30 % acrylamide, we decided to continue with 20 % for now
Pouring a polyacrylamide gel containing an overnight culture, this gel is divided in four, two gels were freeze dried, and two more were incubated overnight at 30 °C with fresh M17 medium
These gels were checked by phase contrast microscopy after incubation overnight, a lot of cells were visible, but we could not distinguish the living of dead bacteria, therefore we decided to continue the experiment with an inducable GFP expressing strain
July 28 - August 1
Preparing a GFP stock of L. lactis NZ9000 with pNZ8048g, and growing an overnight culture of this strain
Inducing the L. lactis NZ9000 with pNZ8048g with different concentrations of ZnSO4, the cells were observed under the microscope and some GFP expression was observed
Figure 1:
The L. lactis NZ9000 strain with pNZ8048g under the microscope, on the left the GFP channel is shown, and on the right the ordinary phase contrast picture is displayed
4 August - 8 August
This time we'll try pouring a gel on ice. This is because during the solidifying of acrylamid there is a lot of heat, we were a bit scared this heat could destroy our cells.
Unfortunately the solidifying process will slow down to a point that it will take more then an hour to complete. We've decided that this wouldn't work, so we continue without using ice.
Poured a gell with the GFP strain. Freeze a half, and the other half was put into the stove.
The next day these were both incubated with ZnSO4 for an hour. After an hour of incubating this didn't give any results. Incubation time should be longer the next time.
Figure 2:
The L. lactis NZ9000 strain with pNZ8048g under the microscope, on the left the GFP channel is shown, and on the right the phase contrast picture is displayed
August 11 - August 15
A polyacrylamide gel with the L. lactis NZ9000 strain with pNZ8048g, we incubated the gels in GM17 media with ZnSO4 for two hours at 30 °C, and observed the gels under the microscope
Some GFP expressing L. lactis was seen under the microscope
Repeating the experiment looking for the best conditions
Figure 3:
The L. lactis NZ9000 with pNZ8048g, seen through a phase contrast microscope, on the right the GFP channel is displayed
August 18 - August 22
Pouring a polyacrylamide gel with an overnight culture of L. lactis NZ9000 with pNZ8048g, the gel was split into several parts, and the parts were observed after certain time-spams divided over two weeks
L. lactis NZ9000 with pNZ8048g seems to be able to survive the polyacrylamide is liquid state and the polymerization process
September 1 - September 4
Nisin diffusion tests performed with the polyacrylamide gel
A GM17 agar plate with L. lactis NZ9000 on it, this is a L. lactis strain that is sensitive for nisin, after which we made three holes in the agar
how will we do this: We will start by pouring gm17 agar plates with the nz9000 strain on it, this is a strain that doesn't have any nisin resistance. While pouring we had 3 empty circles inside this agar plate where we can put in 3 small samples of acrylamid gel.
This acrylamid gel contains the NZ9700 strain, this is a strain that can create nisin. It does this after induction with nisin.
Inside the three holes, polyacrylamide gels with the L. lactis nisin producing strain NZ9700
The three holes had slightly different conditions, one of the three wholes if filled with a gel, which was incubated overnight at 30 °C, the other two were filled with a freshly prepared gel of which one is not induced to produce nisin
Our first try didn't go to well because the gel didn't seem to touch the agar, diffusion wouldn't start.
During the first experiment we hardly received any results, most likely this was caused by the fact that the gel did not touch the agar
Figure 4:
The result of one of the diffusion tests, the halos around the gels shows the range of inhibition
September 8 - September 12
Performed the difussion experiment again, but using better conditions, the plate was incubated overnight at 30 °C
Figure 4 shows the result of a diffusion experiment under improved conditions, the inhibition area around the gel patches indicate the diffusion of nisin through the polyacrylamide gell
Figure 5:
An other diffusion experiment with the nisin producing L. lactis strain through acrylamid.
September 15 - September 19
Some more diffusion experiments were performed, this time the gels were washed before putting them in the agar plate with the nisin sensitive L. lactis strain
September 29 - October 3
During the last few week several time lapse experiments were performed, with all kind of concentration of polyacrylamide gel, and also with agar and agarose gells, in order to L. lactis grow in the gel
Small gels were poured and incubated overnight in GM17 at 30 °C, two types of gels were used, an intact one, and a fractured one, this might have some effect on releasing some L. lactis cells from the gel
Several percentages of polyacrylamide gels were made, from 2.5 % until 15 % (2.5 - 5 - 7.5 - 10 - 12.5 - 15), the intact gels showed no growth, therefore we can conclude that L lactis is not able to grow in any percentage of polyacrylamide gel
From 2.5 % until 15 % L. lactis was able to grow on/in the fractured polyacrylamide gel, no growth was show on the higher percentages
