What biochemical characteristic distinguishes Salmonella from C. freundii?

The biochemical characteristic that distinguishes Salmonella from Citrobacter freundii is urease production. Salmonella species typically do not produce urease, which is an enzyme that hydrolyzes urea to ammonia and carbon dioxide. This lack of urease production is a key identifying feature for differentiating it from C. freundii, which does produce urease. Consequently, when conducting microbiological tests to identify these organisms, the response to urease testing serves as a critical differentiator.

Understanding this enzymatic activity helps in the identification of microorganisms in a clinical or laboratory setting, as the presence or absence of certain enzymes contributes to the overall metabolic profile that microbiologists use to classify and diagnose various bacterial species.