Difference between revisions of "Team:IISc-Bangalore/Hardware/Results"

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<h1 id = "calibration">Calibration</h1>
 
<h1 id = "calibration">Calibration</h1>
  
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<p>Calibration of Version1.1 was done using KMnO4 and milk solutions of different dilutions. V1.1 can hold a test tube containing the sample and measure its optical density (OD). The same electronic circuitry was used to measure the OD values of the sample placed in a cuvette. The OD values of the sample was taken using a spectrophotometer (actual) and the device-V1.1 (measured).
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<p>Before we could try running growth curves with GCODe, we needed to check that its readings were linear. We calibrated the Mini (then called Version 1.1) against a spectrophotometer (Shimadzu UV-1800) at 648 nm by running serial dilutions of KMnO4 solutions and milk.  
 
</p>
 
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<p>The Mini (then called Version 1.1) was calibrated against a spectrophotometer (Shimadzu UV-1800) at 648 nm by running serial dilutions of KMnO4 solutions and milk.
 
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</p>
 
  
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<img src="https://static.igem.org/mediawiki/2017/f/ff/T--IISc-Bangalore--ecoli2.jpg" align ="center">
 
  
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<p>There has to be a better way. That way is GCODe.</p>
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<p>As you can see, the graphs are linear to within experimental error! Data from which these graphs were generated is available at [data link]</p>
  
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<p>GCODe (Growth Curve and Optical DEnsity) is an optical density measurement device that will not only take readings at pre-programmed intervals or continuously, but will also aerate and dilute the culture as required. It can even send you a message when the OD reaches a particular level, just in time to you to start the next stage of your experiment. Fundamentally, it automates the grunt work of growth curves, in a manner that allows you to walk away from the lab, secure in the knowledge that you will be alerted when your cells are ready for you.</p>
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<h1 id="growthcurves">Growth Curves</h1>
  
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<p>Our work stemmed from our own frustrations running growth curves night after night, and was also inspired by the OD meter built by the 2014 Aachen iGEM team. We worked incrementally, starting with a rudimentary box of wiring, designing version after version in response to feedback from the iGEM wetlab team, as they trialled our device, and other labs and professors from across IISc.</p>
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<p>With the knowledge that GCODe's readings are linear, we are now ready to run Growth Curves! There is a slight hitch, however. Optical Density is calculated using Beer-Lambert's Law, which states that Absorbance = Absorbance coefficient x Concentration x Path Length. But we realised that the path length and epsilon are different for our optical system as compared to the spectrophotometer. However since the concentration will still be the same in both cases, the OD will be proportional. We can then compare the graphs by normalizing, ie dividing by any one reading.</p>
  
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<p>We currently have two versions of GCODe - The GCODE Mini and the GCODe Pro.
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<p>Growth curves of Salmonella typhimurium (STMwt14028) and Escherichia Coli were made. The optical densities were simultaneously measured using a spectrophotometer at wavelength 600nm and our device GCODe Mini.</p>
  
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The GCODe Mini has been developed, fabricated, tested and fully documented. The GCODe Pro is still under development and is in its third version.  
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<img src="https://static.igem.org/mediawiki/2017/d/d4/T--IISc-Bangalore--hardware_gc1.jpg" align ="left">
  
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<img src="https://static.igem.org/mediawiki/2017/3/3c/T--IISc-Bangalore--hardware_gc2.jpg" align ="right">
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<h1 id="growthcurves">Growth Curves</h1>
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<h2>Intro</h2>
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<p></p>
  
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<p>The GCODe Mini is a sleek black acrylic cuboid that houses a test tube that will hold your culture. Connect the Mini to your laptop via USB, tell it what to do with our associated software, place it in the shaker-incubator, press Start … aaand you’re done !</p>
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<img src="https://static.igem.org/mediawiki/2017/f/f2/T--IISc-Bangalore--ecoli1.jpg" align ="left">
  
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<img src="https://static.igem.org/mediawiki/2017/f/ff/T--IISc-Bangalore--ecoli2.jpg" align ="right">
  
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<p>Notice that the E. Coli readings from the Mini form an even smoother curve than those from the spectrophotometer! This is probably because the GCODe readings were taken instantaneously, while it takes time to load the cuvette into the spectrophotometer and take a reading, allowing lots more opportunities for human error.</p>
  
 
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Revision as of 13:11, 28 October 2017

  1. Calibration
  2. Growth Curves

Calibration

Before we could try running growth curves with GCODe, we needed to check that its readings were linear. We calibrated the Mini (then called Version 1.1) against a spectrophotometer (Shimadzu UV-1800) at 648 nm by running serial dilutions of KMnO4 solutions and milk.

As you can see, the graphs are linear to within experimental error! Data from which these graphs were generated is available at [data link]

Growth Curves

With the knowledge that GCODe's readings are linear, we are now ready to run Growth Curves! There is a slight hitch, however. Optical Density is calculated using Beer-Lambert's Law, which states that Absorbance = Absorbance coefficient x Concentration x Path Length. But we realised that the path length and epsilon are different for our optical system as compared to the spectrophotometer. However since the concentration will still be the same in both cases, the OD will be proportional. We can then compare the graphs by normalizing, ie dividing by any one reading.

Growth curves of Salmonella typhimurium (STMwt14028) and Escherichia Coli were made. The optical densities were simultaneously measured using a spectrophotometer at wavelength 600nm and our device GCODe Mini.

Notice that the E. Coli readings from the Mini form an even smoother curve than those from the spectrophotometer! This is probably because the GCODe readings were taken instantaneously, while it takes time to load the cuvette into the spectrophotometer and take a reading, allowing lots more opportunities for human error.