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Design
The [http://www.nature.com/nature/journal/v463/n7279/abs/nature08753.html paper] oscillatory system is based on, used microfluidic devices to physically constrain the host cells. This was necessary to induce and monitor oscillatory behaviour of a population of e.coli cells. Such microfluidic devices are very expensive and only usable for one experiment. Due to this we set out to find a cheap alternative for these microfluidic devices. Eventually we designed our own flow device, of which the design is seen in figure 1.
Fig.1: Wire frame model of designed flow device.
Bacterial growing platforms
This flow device can accommodate two bacterial growing platforms, a micro-sieve and a micro-dish. The micro-sieve as depicted is figure .. are membranes which have evenly distributed pores of 200 nm in diameter. These membranes are used in dairy industry to sterilise dairy products by removing micro-organism through filtration. Through filtration a cake of cells will form on the membrane, potentially giving us a platform capable of inducing and giving a mean of monitoring oscillatory behaviour of a population of e. coli cells.
Fig.1: Design flow device made in google sketchup
The micro-dish contains porous wells, in which the cells can be physically constrained. It is placed in the socket of the dish, which allows a fluid to be flown over the wells. This fluid can be used to supply the cells with nutrients and wash away excess AHL and cells if necessary. Figure 2 shows a schematic of the device. The inflow and outflow1 can be used to flush the device with fresh medium. The use of outflow2 depends on the bacteria growing platform. In the case of the micro-sieve it can be used to create an under pressure, e.g. with a syringe, to trap the bacteria on the sieve. When using a micro-dish, it can optionally be used to bottom-feed the bacteria in the wells and/or supply additional substances to initalize the oscillatory behaviour of the system, e.g. IPTG in the case of the pRight/lacI hybrid promoter for the streamligned oscillator.
Fig.2: Schematic of the micro-fluidic device depicting the position of in- and outflow
Left: Production of the device in the Wageningen University workshop
