Lab method
EMB agar concept
Green metallic sheen = E. coli
High-yield clue
A green metallic sheen on EMB is the classic clue for strong lactose fermentation by Escherichia coli.
Overview
Eosin methylene blue is a selective and differential medium concept that inhibits Gram-positives and distinguishes lactose fermenters by colony color and sheen.
Classification
- Selective and differential medium
- Inhibits Gram-positive growth
- Eosin/methylene blue indicators
Lab & identification clues
- Green metallic sheen = vigorous lactose fermenter (E. coli)
- Dark/purple colonies = slower fermenters (Klebsiella)
- Colorless colonies = non-lactose fermenters
- Dyes suppress Gram-positive organisms
Associations
- E. coli sheen study clue
- Lactose vs non-lactose fermenter framing
- Enteric Gram-negative differentiation
Commonly confused with
- MacConkey agar
- TSI agar
Frequently asked questions
What is EMB agar concept?
Eosin methylene blue is a selective and differential medium concept that inhibits Gram-positives and distinguishes lactose fermenters by colony color and sheen.
What is the high-yield clue for EMB agar concept?
A green metallic sheen on EMB is the classic clue for strong lactose fermentation by Escherichia coli.
What is EMB agar concept associated with?
EMB agar concept is associated with E. coli sheen study clue, Lactose vs non-lactose fermenter framing, and Enteric Gram-negative differentiation.
What is EMB agar concept commonly confused with?
EMB agar concept is commonly confused with MacConkey agar and TSI agar.
Original concept summary for coursework. Sources checked: OpenStax Microbiology 2e and NCBI Bookshelf Medical Microbiology; reviewed 2026-06. Describes vocabulary and interpretation concepts only; not a lab protocol and not for handling specimens or identifying patient isolates.