Posts by: BioSciSam


Bioreactor: First look and test run

So, we have kindly been donated a lovely bioreactor. 🙂 As a big fan of these bits of kit I thought I’d try and document my first look as I try to make sense of the many wires and widgets provided. Here’s the vessel itself. A lovely bit of kit that can be used to contain and monitor a fermentation reaction in a closed system. It’s a somewhat dated device and the electronic control systems dwarf the unit and are housed in what the documentation refers to as ‘The Mainframe’!: This system allows you to monitor the levels of dissolved gases, pH, temperature and agitation using various probes. In a modular way, each probe has it’s own control unit which stack up to build your control system.   The reactor system is also comprised of some very nice widgets and nice metal components 🙂     Also, designed as another port insert component. The gauge measures the head pressure generated by the gases released in fermentation processes.   The 180V at 0.5 amp motor which drives the central propeller that provides agitation to the reaction is controlled by an encoder. After much perusing of the schematics and confusion I managed to set up the agitation unit with the reactor and set it running: Sorry about the poor photos and vid/sound!   Next steps: Look at the probe control circuitry more (could this whole thing run off a Pi / Arduino now?).. I’d like to scale up one of transformed strains, especially miraculin yeast in this.  

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Chromatography of Biomolecules

As a simple demonstration of the chromatographic separation of plant pigments I followed this procedure: a leaf sample (borrowed from one of my jalapeno plants) was ground up with a small volume of acetone to create the crude extract. As much of the liquid as possible was transferred to an eppendorf tube and then spun down at high speed (13k rpm) in a microfuge to sediment out any particulates. The supernatant was then transferred to a plastic test tube and placed on a heating block at approximately 70degC to evaporate the acetone. (this step took several hours to complete) The solids remaining in the tube were then resuspended in hexane. Meanwhile, a separation column was created using a 10ml BD syringe, a small plug of cotton wool and a couple of grams of aluminium oxide. (This is the stationary phase of the column.) The column is first wetted with a few mLs of hexane. The column should be saturated in hexane before application of the sample. The sample from step 4 was then added to the top of the column with a pasteur pipette and a small amount of pressure applied using the plunger of the syringe. Initially clear hexane flows through the column followed by a distinctive yellow fraction (most probably carotenoid pigments), which was caught in another test tube. [While this occurs the green chlorophyll pigments have a higher affinity for the aluminium oxide solid phase than the hexane mobile phase and remain bound to the matrix of the column.] Once all of the yellow phase has been removed a few mLs of acetone were then added to the top of the column. After a small amount of clear mobile phase left the column it was followed by a distinctive green phase. [this constitutes the chlorophylls which...

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