What causes E. coli to form metallic green colonies on EMB agar?

Question

I have read that the acid production causes methlene blue to precipitate. I have also read that the high acid levels causes an eosin-methylene blue complex to form. Which is right?

Answer 1

Looks like it's a function of the pH, specifically large amounts of acid produced by the bacteria which cause the two dyes used to form and amide bond.