Effect of subinhibitory concentrations of cumin (Cuminum cyminum L.) seed essential oil and alcoholic extract on the morphology, capsule expression and urease activity of Klebsiella pneumoniae

Cuminum cyminum L., commonly known as cumin, is a plant with a considerable reputation. The aim of this work was to study the activity of cumin seed essential oil and alcoholic extract against Klebsiella pneumoniae ATCC 13883 and clinical K. pneumoniae isolates by evaluating the effect of subminimum inhibitory concentrations (sub-MICs) on cell morphology, capsule expression and urease activity. Growth of K. pneumoniae strains exposed to sub-MICs of C. cyminum extracts resulted in cell elongation and repression of capsule expression. Urease activity was decreased. The major constituent of the oil determined by gas chromatography/mass spectrometry was cumin aldehyde.