Difference between revisions of "Team:elan vital korea/Protocol"

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             <a href="https://2015.igem.org/Team:elan_vital_korea">
 
             <a href="https://2015.igem.org/Team:elan_vital_korea">
 
                 <img class="displayed" src="https://static.igem.org/mediawiki/2015/d/d5/ElanVital_Logo.png">
 
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Growth on LB Agar plates provides colonies originating from one single bacteria cell. <br><br>
 
Growth on LB Agar plates provides colonies originating from one single bacteria cell. <br><br>
 
<b> 5. </b><br>
 
<b> 5. </b><br>
Just before pouring the solution into petri dishes, an antibiotic can be added for resistance selection. <br> We  
+
Just before pouring the solution into petri dishes, an antibiotic can be added for resistance selection. <br> We
 
followed the normal working concentrations such as: <br>
 
followed the normal working concentrations such as: <br>
  
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<b> 6. Material to make LB plates: </b><br>
 
<b> 6. Material to make LB plates: </b><br>
NaCl (Sodium Chloride) <br>  
+
NaCl (Sodium Chloride) <br>
Bacto™ tryptone <br>  
+
Bacto™ tryptone <br>
yeast extract <br>  
+
yeast extract <br>
Bacto™ agar <br>  
+
Bacto™ agar <br>
ddH2O (triple distilled water) <br>  
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ddH2O (triple distilled water) <br>
1000x chloramphenicol or ampicillin <br> <br>  
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1000x chloramphenicol or ampicillin <br> <br>
 
</font>
 
</font>
 
</p>
 
</p>
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4) Autoclave for 20 min within 2 hr <br>
 
4) Autoclave for 20 min within 2 hr <br>
 
5) Keep it cool until it reaches around 40-50 °C <br>
 
5) Keep it cool until it reaches around 40-50 °C <br>
6) Add 200 μL of 1000x chloramphenicol and gently stir it. Be careful not to shake the bottle too long/hard so that  
+
6) Add 200 μL of 1000x chloramphenicol and gently stir it. Be careful not to shake the bottle too long/hard so that
 
bubbles are created. <br>
 
bubbles are created. <br>
7) Pour into empty petri dishes just enough to cover the surface (~20 mL per plate). In case that bubbles are in  
+
7) Pour into empty petri dishes just enough to cover the surface (~20 mL per plate). In case that bubbles are in
the plate, heat the plate surface carefully with a burner only until the bubbles are burst but the solution is  
+
the plate, heat the plate surface carefully with a burner only until the bubbles are burst but the solution is
 
heated. <br>
 
heated. <br>
 
8) Leave the plates at room temperature around one hour until it is solidified. <br>
 
8) Leave the plates at room temperature around one hour until it is solidified. <br>
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<P style="text-align:center;">
 
<P style="text-align:center;">
 
     <font color="white">
 
     <font color="white">
1. We used LB medium almost every day, so we have  
+
1. We used LB medium almost every day, so we have
  
prepared LB medium many times. To prevent  
+
prepared LB medium many times. To prevent
  
contamination, we only used LB medium made within  
+
contamination, we only used LB medium made within
  
 
three days.
 
three days.
  
2. Materials: NaCl, Trypton, Yeast Extract, and ddH2O (triple  
+
2. Materials: NaCl, Trypton, Yeast Extract, and ddH2O (triple
  
 
distilled water)
 
distilled water)
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3. Equipment: autoclave, electronic scale.
 
3. Equipment: autoclave, electronic scale.
  
4. Process  
+
4. Process
  
 
We usually make 200 liter LB bottle
 
We usually make 200 liter LB bottle
  
1) 2 g of NaCl to a final concentration of 0.17 M  
+
1) 2 g of NaCl to a final concentration of 0.17 M
  
 
2) 2g of 1%(w/v) Bacto™ tryptone
 
2) 2g of 1%(w/v) Bacto™ tryptone
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</h5>
 
</h5>
 
<br>
 
<br>
 
<P style="text-align:center;">
 
<font color="white">
 
Our team, Elan Vital Korea, addressed the problem of rapidly detecting antibiotic-resistant bacteria. We were interested in <br>
 
a rapid and efficient method of antibiotic resistance detection, and we believed that such a method could be engineered <br>
 
using quorum sensing.  Our hypothesis was that we would be able to use quorum sensing – a method bacteria <br>
 
use to communicate with each other – to make the cells quickly report the existence of antibiotic-resistant bacteria
 
<br><br>
 
 
By quorum sensing, bacteria can perform many cooperative functions, such as biofilm formation, antibiotic production, motility,<br>
 
swarming, virulence, and much more.  While most quorum sensing takes place between bacteria of the same species, there are<br>
 
cases of interspecies quorum sensing.  Auto-inducers affect the gene expression of the bacteria once they reach <br>
 
a certain concentration threshold.  Bacteria using quorum sensing usually produce small amounts of <br> auto-inducers, so that the concentration of auto-inducers are affected by the concentration of the bacteria. <br>
 
In other words, quorum sensing, in essence, regulates gene expression in response to cell density. <br>
 
Using quorum sensing, bacteria are able to act in unison, as if they were a single organism.<br><br>
 
 
Quorum sensing is widely used by various bacteria for various functions, so each uses a slightly different auto-inducer <br>
 
so the signals are not mixed up.  In general, gram-negative bacteria use a class of molecules called N-acyl <br>
 
homoserine lactones, or AHL, while gram-positive bacteria use short processed polypeptides.  <br><br>
 
</font>
 
</p>
 
 
  <a href="#top" rel="" id="top" class="anchorLink">
 
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<br><br>
 
 
For example, the picture below represents the quorum sensing mechanism in the bacteria vibrio fisheri.  Vibrio fisheri is a bacteria <br>
 
that produces bioluminescence, and is famous for revealing quorum sensing for the first time.  Vibrio fisheri uses quorum sensing <br>
 
to produce light in high cell density, and researchers first discovered quorum sensing from examining vibrio fisheri.<br><br>
 
 
In vibrio fishri, quorum sensing involves LuxI and LuxR as well as AHL.  LuxI is the protein that produces AHL, and LuxR forms a complex <br>
 
with AHL to affect the regulation of genes.  In this case, it produces luciferase, which produces bioluminescence. Furthermore, the process <br>
 
also boosts the production of LuxI, which creates a positive feedback loop.  This AHL-LuxR quorum sensing mechanism is one of the most well <br>
 
known gram-negative quorum sensing pathways, and it can be <br> engineered to affect almost any coding sequence we like.<br><br>
 
 
</font>
 
</p>
 
 
<img class="displayed" src="https://static.igem.org/mediawiki/2015/2/2e/Graphics-03-25.png">
 
<br>
 
 
<p style="text-align:center;">
 
<font color="black">
 
For the project, we have developed a reporter cell that expresses GFP in the presence of the QS signaling molecule
 
acyl homoserine <br>
 
lactone (AHL).  Our test cells (which act as a simulation of antibiotic-resistant bacteria) express lactonase, <br>
 
which breaks down AHL.  In our experimental system, test cells should signify their presence by breaking down AHL and <br>
 
preventing GFP expression in reporter cells. <br>
 
</font>
 
</p>
 
<br>
 
<img class="displayed" src="https://static.igem.org/mediawiki/2015/6/6e/Hr_black.jpg" width="80px" height="2px">
 
<br>
 
 
<h5 style="text-align:center;">
 
<font color="black">
 
Experiment: Process and Results<br>
 
</font>
 
</h5>
 
<br>
 
 
<P style="text-align:center;">
 
<font color="black">
 
There are many ways of utilizing quorum sensing for medicinal use, and one of the most intuitive and most well-known methods is quorum quenching. <br>
 
</font>
 
</p>
 
 
<a href="#top" rel="" id="top" class="anchorLink">                    <img class="displayed" src="https://static.igem.org/mediawiki/2015/5/5b/Scroll_arrow_top_Black.png"></a> 
 
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<br><br>
 
<P style="text-align:center;">
 
<font color="white">
 
Quorum quenching takes advantage of the fact that quorum sensing also plays a role in  expressing virulence, and interferes with the quorum sensing that <br>
 
produces virulence. There are many ways of utilizing quorum sensing for medicinal use, and one of the most intuitive and most well-known methods is quorum quenching. <br>
 
Quorum quenching takes advantage of the fact that quorum sensing also plays a role in expressing virulence, and interferes with <br>
 
the quorum sensing that produces virulence. However, for our project this year, we decided to focus on engineering a detection method for antibiotic resistance. <br>
 
For the project, we created a test plasmid and a reporter plasmid.  We then transformed competent E. coli with the plasmids to produce a  <br>
 
test cell and a reporter cell.  As shown in the picture below, the test cell produces lactonase, which breaks down AHL, a common auto-inducer in <br>
 
gram-negative bacteria.  And the reporter cell produces GFP (or luciferase) which creates a visible difference that we can detect.  <br>
 
Both plasmids were engineered using the BioBrick DNA recombination process.  With such a set up, it will be possible to detect the presence of the test cell, or lactonase.<br><br>
 
 
For the confirmation of our hypothesis, we conducted some experiments. Ideally, mixing AHL with the test cell will break down the AHL. And, adding <br>
 
the reporter after that will not result in any fluorescence. But, if we do the same process with the control bacteria instead of the test cell, <br>
 
there will be fluorescence. As theorized, the control experiments produced fluorescence, but the experiments with the test cell produced no  fluorescence. <br><br>
 
 
<img class="displayed" src="https://static.igem.org/mediawiki/2015/9/9d/Graphics-26.png">
 
<br><br>
 
<a href="#top" rel="" id="top" class="anchorLink">
 
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<br><br>
 
<h5 style="text-align:center;">
 
<font color="black">
 
Expected Benefits
 
</font>
 
</h5>
 
<br><br>
 
 
<P style="text-align:center;">
 
<font color="black">
 
Thanks to bacteria’s ability to make quick and profound changes in gene transcription, quorum sensing can be <br>
 
used to detect a low amount of signaling molecules and report their presence quickly.  With further <br>
 
research and thorough engineering applications, it may be possible to detect other antibiotic-resistant bacteria<br>
 
that are unknown until now.<br><br>
 
 
If it is proven as valid and effective through sufficient tests, this technique could be disseminated to <br>
 
hospitals and clinics to test the presence of antibiotic-resistant bacteria. <br>
 
We hope that this technique, if properly adjusted for functional advancement, can detect antibiotic-resistant <br>
 
bacteria in a relatively short time with only a small amount of sample secured from the patient. <br>
 
This would provide an advantage over the traditional detection methods, culture-based approaches which require <br>
 
one or several days of incubation period.<br><br>
 
 
Because chemicals involved in species-specific quorum sensing is very specific, it might be possible to <br>
 
dramatically resolve the problem of overnight incubation.  Because an initial sample from <br>
 
a patient is usually contaminated and has only a small concentration of the wanted bacteria, it is often <br>
 
impossible to detect any antibiotic-resistance without purification and amplification through overnight <br>
 
incubation.  But because species-specific quorum sensing involves biochemical that are<br>
 
highly specific, and the quorum sensing chemicals are not affected as much by the contamination, the method <br>
 
utilizing quorum sensing might be applied with relatively less purification processes.  Also, because <br>
 
some quorum sensing mechanisms have built in positive feedback, with the right engineering, <br>
 
the mechanism could work with only a little amplification process.<br><br>
 
 
More innovative detection methods such as quantitative PCR(qPCR) or microarrays, and advanced molecular <br>
 
detection (AMD) are based on accumulated previous data and, thus, render very accurate results, but <br>
 
they require complicated  procedures and heavy equipment.  On the other hand, this quorum sensing-based detection <br>
 
method will provide benefits to patients with handy procedure and quicker detection results. We believe quicker <br>
 
and easy detection of antibiotic-resistant bacteria will lead to better containment of such <br>
 
dangerous bacterial strains.<br><br>
 
 
</font>
 
</p>
 
 
<br>
 
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<h5 style="text-align:center;">
 
<font color="white">
 
Reference
 
</font>
 
</h5>
 
<br><br>
 
 
<P style="text-align:center;">
 
<font color="white">
 
Antibiotic Resistance Threat in the United States 2013, US Department of Health and Human Services, <br>
 
Center for  Disease Control and Prevention About Quorum Sensing<br><br>
 
 
Annual Review of Microbiology, Volume 55:pp 165-199 (volume publication date, October 2001) Melissa B.Miller and Bonnie L. <br>
 
Bassler Department of Molecular Biology, Princeton University, Princeton, New Jersey <br><br>
 
 
Bacterial Quorum Sensing: Its Role in Virulence and Possibilities for Its Control Steven T. Rutherfold and Bonnie L.Bassler. <br>
 
Cold Spring Harb Perspect Med. 2012.2, Cold Spring Harbor Laboratory Press<br><br>
 
 
Quorum Sensing: Bacteria Talk Sense Costi D. Sifri, Oxford Journals, Volume 47, Issue 8 Pp 1070-1076, 2015 <br> Infectious Diseases Society of America <br><br>
 
 
Bacterial Quorum Sensing in Pathogenic Relationships Teresa R. de Kievit, Barbara H.Iglewski, Infection and Immunity, <br>
 
Volume 68, September 2000, 2000 American Society for Microbiology
 
</font>
 
</p>
 
 
 
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Revision as of 15:29, 13 September 2015








WETLAB
-Protocol-


PROTOCOL

We conducted our experiments by following the protocols below. As an official procedure, lab workers should understand the lab experiment
assigned to them along with safety procedures before starting lab work. The protocols are arranged according to the order of experiments we followed.


Protocols to handle enzymes.

1.
Enzymes used in our project, such as AHL, must be stored in low temperature. The enzymes must be stored in the freezer
when they are not used, and must be put on ice when taking them out of the freezer for an experiment.

2.
Enzymes should be added last to the solution, because enzymes are sensitive to inactivation by pH and ionic conditions that
deviate from their storage and reaction buffers. After adding enzymes, the mixed solution should be mixed completely.


Protocols to store materials and maintain
usage history of each material.

1.
Reporter cell, test cell and competent cell (Top 10 invitrogen) must be kept at 4°C and frequently used enzymes, reagents,
DNA plasmids should be kept at −20°C in the freezer.

2.
We use AHL as protein enzymes. AHL must be kept at lower temperature (4°C or lower) for the recurring use.
AHL can be destroyed easily when it is stored and/or handled in improper temperature.

3.
We use triple distilled water (or DDH2O) to make LB broth. Triple distilled water is kept at
lab temperature (around 18 °C or lower).



To The Top


4.
Other materials such as yeast and NaCl are stored and maintained under the responsibility of Gachon Molecular Biology Lab.
5.
We have to record the history of each material, including if plasmids/reporter cell/ test cell/ AHL have been frozen and if so, when it is used.



LB Agar Plates and Addition of Antibiotics

1.
We have used LB (solidified lysogeny broth), rich growth medium for E.coli, in our experiments almost all the time.

2.
All the needed chemicals including yeast extract must be prepared beforehand.

3.
Autoclave must be available.

4.
Growth on LB Agar plates provides colonies originating from one single bacteria cell.

5.
Just before pouring the solution into petri dishes, an antibiotic can be added for resistance selection.
We followed the normal working concentrations such as:
- chloramphenicol: 25 μg/mL
(Chloramphenicol stock is dissolved in ethanol)
In case of using ampicillin: 100 μg/mL
- normal stock concentrations:1000-fold

6. Material to make LB plates:
NaCl (Sodium Chloride)
Bacto™ tryptone
yeast extract
Bacto™ agar
ddH2O (triple distilled water)
1000x chloramphenicol or ampicillin

To The Top

7. Process
We usually make 1liter bottle for LB Agar
1) 200 mL LB prepared fresh, non-autoclaved
2) 3 g agar
3) Shake until all solids are dissolved
4) Autoclave for 20 min within 2 hr
5) Keep it cool until it reaches around 40-50 °C
6) Add 200 μL of 1000x chloramphenicol and gently stir it. Be careful not to shake the bottle too long/hard so that bubbles are created.
7) Pour into empty petri dishes just enough to cover the surface (~20 mL per plate). In case that bubbles are in the plate, heat the plate surface carefully with a burner only until the bubbles are burst but the solution is heated.
8) Leave the plates at room temperature around one hour until it is solidified.
9) Solidified plates should be turned upside down for a few hours at room temperature, then stored at 4°C.


LB Medium

1. We used LB medium almost every day, so we have prepared LB medium many times. To prevent contamination, we only used LB medium made within three days. 2. Materials: NaCl, Trypton, Yeast Extract, and ddH2O (triple distilled water) 3. Equipment: autoclave, electronic scale. 4. Process We usually make 200 liter LB bottle 1) 2 g of NaCl to a final concentration of 0.17 M 2) 2g of 1%(w/v) Bacto™ tryptone 3) 1g of 0.5% (w/v) yeast extract 4) ddH2O to 200 mL 5) Autoclave for 20 min within 2 hours 6) Keep at room temperature



Overnight Cultures with Antibiotics