Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

LB, TB media, and yeast extract are also yellow but at the heart of the question. What chemical(s) make E. coli yellow?

share|improve this question
If I had to guess, I would say FMN/FAD. –  bobthejoe May 14 '12 at 20:58
It's likely the proteins (general, nebulous answer). Yeast extract of course tints the LB and TB media. There is obviously a range of compounds involved because we are seeing the result of non-yellow wavelengths being absorbed. –  leonardo May 18 '12 at 21:33

2 Answers 2

You will be surprised that when describing the colonial morphology of E. coli on a Blood agar plate, the word choice for colour is "grey". I believe that user leonardo up there had a very good explanation about this "yellowish colour" question.

share|improve this answer

I think of E. coli being more white than yellow. When you compare E. coli and S. aureus on an agar plate, the Staph colonies have a much more distinctive yellow tint. The yellow tint in Staph colonies is due to staphyloxanthin, a carotenoid pigment.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.