E. coli Fermentation Profile: Carbohydrate Utilization for Laboratory Identification

Escherichia coli fermentation patterns on carbohydrate media are classic microbiology identifiers:

Substrate	Fermentation	Products
Glucose	Positive	Acid (lactic), gas (CO₂), ethanol
Lactose	Positive (rapid)	Acid, gas
Maltose	Positive	Acid, gas
Sucrose	Positive	Acid, gas
Mannitol	Positive	Acid, gas
Sorbitol	Positive (most strains)	Acid, gas
Dulcitol	Positive	Acid, gas
Inositol	Negative	—
Adonitol	Negative	—
Salicin	Negative	—

Diagnostic Utility

• Lactose + gas + indole+ + methyl red+ + Voges-Proskauer– + citrate– = classic E. coli IMViC profile (++––).
• Sorbitol-negative strains = E. coli O157:H7 (uses sorbitol-MacConkey for screening).
• Commercial systems (API 20E, VITEK, MALDI-TOF) now standard; fermentation patterns remain foundational knowledge.