It depends. If you want to study the cell growth and differentiation then, acridine may be used, Sytox orange may be used for nucleic acid staining or eosin may be used for cytoplamic study.

Strangely enough, food coloring works reasonably well too.

thank you for your comment. I want to make different for my antagonistic bacteria after application with other bacteria. Is it possible using acridine or sytox orange or food coloring works?

Dear Loekas,

as Akanksha has written, it "depends" what you are doing/what the task of your observations (bacterial culture?) should be. Also whether you prefer observing your bacteria by fluorescence or only transmitted light microscopy.

For the latter, I think, most of the basic dyes, like Trypan Blue, Toluidine Blue, perhaps even methylene blue (e.g. Loeffler's) and others perhaps could be used too (intravital staining). An interesting general view you can find at: http://www.microrao.com/staining.htm

Also, I would like to point you to:

http://en.wikipedia.org/wiki/Gram_staining , where some useful informations on staining bacteria can be found too.

If you can use/if you think of e.g. GFP-transfection of one of the bacteria spec. too, see: http://www.biomedcentral.com/1471-2482/2/6

Best wishes and good luck,

Wolfgang Muss, Salzburg-Austria

If you want to be able to distinguish one population of bacteria from another population of bacteria after mixing the two populations, I would suggest labelling ONE population with CFSE (carboxyfluorescein succinimide ester). Briefly, this compound readily penetrates living cells, where it is activated inside the cell and becomes fluorescent (green, similar excitation/emission to FITC or GFP). Some people have reported using this for bacteria at http://www.protocol-online.org/biology-forums-2/posts/8852.html

However, the fluorescence will become diluted with each cell division (by half), so it is not a permanent stain. If you need a permanent stain, I would suggest a GFP transfection as recommended by Dr. Muss (above).

Dear Dr. Muss and Dr. Steel, thank you for your useful information. Indeed I need the permanent stain for Pseudomonas fluorescens in which the bacteria has fluorescent color. I need another stain for the bacteria, e.g. red or blue or purple color. For GFP-trasfection I have read as Dr. Muss suggestion and the method used a suspension of green fluorescent protein. The bacteria has already green fluorescent color. Is there any color beside the fluorescent one?

Best regards,

Loekas, Indonesia

Which dye's preferable for O and H antigen suspension?