Germ Tube Formation of Candida albicans in Corn Meal Broth Using the Non-Slip Slide Glass Incubation Method

Candida albicans IFO 1385 yeast cells dominantly develop germ tubes in a dilute corn meal broth at 37°C. For germ tube (GT) development the broth concentration is optimal at 75% of the original, and the inoculum is optimal at 105 cells/mL. Incubation procedures were compared and the non-slip slide glass incubation (NSSI) method was found to be more available than the tube incubation method or slid-covered slide glass incubation method. The GT formation was completed in 1 to 2 h in the NSSI method and clear-cut GTs were observed under optical microscopy. GTs were formed in all 111 test-strains of C. albicans but not at all in other species of Candida. Therefore, under optimal conditions, the rate of identifying C. albicans is 100%, demonstrating that GT detection with the NSSI method is a rapid and reliable identification method. The humid NSSI method is suited for continuous observation of a GT. The initially formed GT elongated to resemble a true hypha, attaching no chlamydoconidium. The hypha subsequently dissociated yeast-like cells.