Question

in the EMB Agar why are the organisms growing in the media gram-negative

Answer 1

Question: In the EMB Agar, why are the organisms growing in the media gram-negative?

Answer: Eosin methylene blue (EMB) agar is a selective medium for gram-negative bacteria. The EMB Agar contains lactose, sucrose, eosin and methylene blue. The dyes eosin and methylene blue found in the medium inhibit the growth of the gram-positive bacteria, thus allowing the gram-negative bacteria to grow in the nutrient agar. Hence only gram-negative bacteria grow on EMB Agar. It is used to differentiate various gram-negative bacteria belonging to the bacterial family Enterobacteriaceae. e. g Escherichia coli.