Food colouring agar plates - Do you think it will affect cells? (Oct/27/2009 )

Hi,

I read this article recently about adding food colouring to agar plates for easy identification of which plates have which antibiotics added & thought it would be quite neat to try out. Eg. blue for ampicillin plates, red for kanamycin etc... A few people in my lab have some concerns about whether or not the dye would say incorporate into the plasmid DNA etc... Do you think the food colouring would have an affect on DNA? Agar plates would be used for standard transformations from which plasmid DNA would be maxi prep'd. The exact colours in the food dye are tartrazine green S in green and sunset yellow and ponceau 4r in red.

Would love to hear what people think about this!

Our lab just puts a colored stripe or two on the side of the plate depending on which antibiotics are added. I've never had anyone get confused about what type of plate they're using.

microgirl on Oct 27 2009, 03:57 PM said:

Thats quite handy too! Colouring the actual agar is kinda groovy though!

Groovy - yes! But if you get weird results how will you explain whether they're due to the food coloring or not?

microgirl on Oct 27 2009, 05:32 PM said:

This is very true! Thats why i was wondering if people have used them before & if they have encountered any problems!

you could use the dyes that we already add to our loading buffers when running agarose gels.

You can't really question the use of those dyes.

As for the other food dyes. It should be okay, but you could run a test just to prove the point to your more reserved labmates.

hhmmm... anybody want to start an international standard for colouring and associated antibiotic

Would also "groovy", if the colour changes or becomes undecided with changing/different pH or attack of some enzymes of the micro-organisms...then chaos would be perfect.

We use
amp - orange
kan - red
cm - green (like chlorophyl)
tet - yellow (that's the color)

I definitely think we need a standard.

... as long as the red dye didn't make the cells hyperactive!

hobglobin on Oct 27 2009, 11:21 AM said:

True. Definitely no ph dependent dyes. No dyes that change to a different colour when metabolised (especially by e coli). A dye becoming colourless is okay.

Given the number of dyes there are, it should be possible to find useful dyes. We just need to test a few dyes and see their effect.