Part:BBa_K177038:Experience

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UNIQ4b9d2ae8ea4922fa-partinfo-00000000-QINU UNIQ4b9d2ae8ea4922fa-partinfo-00000001-QINU UPO-Sevilla Team ([http://2011.igem.org/Team:UPO-Sevilla Wiki]) Two are the most important features of a flip flop: Time of the change of state and stability when the inducer is retired.Then these are the condition that we have observed to characterize this genetic device. I set overnight inoculums inducing a condition (adding 0,1 mM IPTG or growing at 42ºC). The morning after I make a 1/100 dilution, and let it grow until de optic density reaches 0,2. In that moment I change the conditions, to test the change between states or just retire the inducers, to observe the stability of one state in a long time.

It’s important not to use LB media, because it contains cyclic aminoacids which make it fluorescent. For all this experiments we used Minimal Media supplemented with 0,1% casminoacids. Another problem we faced is that RFP is also excited in the wavelength we use for GFP, making our measure a little bit inaccurate. A solution to this may be insert the bistable in the bacterial chromosome, using the Mini-Tn7 based system my team-mate has developed for biobricks. The less copies of the construction, the better the regulation is, because there is more repressors for each copy of the promoters.

Two repetitions of the switch were made, giving unequal results as it is shown in the graphs. We expect this great variation to be reduced in the improved models we are developing.

We’ve only tried the stability of only the RFP state, finding out it last 16 h at least. This effect is very noticeable when the growth takes place in a plaque, where you can see the change of colour without UV-light.