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Staining Bacteria - There is a wide variety of stains, does it matter which one I use? (Nov/01/2005 )

For my science project, I have to stain bacteria (E. coli). I was thinking of using Methylene Blue Stain, will this be alright? It comes in a 1 oz container, but will that be enough for 15 full petri dishes? How much do I drop in each petri dish. The stain I will buy will probably come from the Science Company at . Thanks for your advice!


why dont you do gram staining.i think that would be better than methylene blue,coz gram staining helps u differentiate gram positive bacteria from gram negative bacteria(as u r using E.coli which is also a gram negative bacteria).ur going to do ur project only on E coli right then pick up one colony from each plate and do gram staining to confirm tat only gram negative org(may be E coli)has grown in ur plate and also c the morphology of the colonies in each plates if u find any difference do gram staining and find out whether they are gram positive or negative confirm that u have got only E coli in ur plates u have to do biochemical test.



I agree that a gram stain is probably a good choice, but the important question is, do you know how to stain bacteria properly?


There are loads of stains, all binding to different structures and biochemicals in cells - if you just want to be able to see your E. coli under the microscope then methylene blue is fine. If you are feeling more adventurous, then try the Gram staining procedure - if you can get something Gram positive as well as your E. coli I am sure it would look cool.

To stain with Meth blue. you should pick colonies of E. coli and drop it on a clean glass slide, add a drop of water, smear it over the slide, let it dry COMPLETELY (say for an hour) and then wave the slide through a Bunsen flame a couple of times. I would then cover the slides with 0.1 % (w/v) methylene blue (1 g in 1000 mL water) for two minutes and then wash off with water. Let dry and observe the little guys!

Hope this helps biggrin.gif