Abstract

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Growth pattern and mycelia formation of two strains O (Oral isolate) and G (genitourinary tract isolate) of Candida albicans in horse-serum, MSB and RPMI 1640 media indicates that the first medium promotes filamentation in both strains while MSB initiates medium mycelium formation for O strain and RPMI stimulates the yeast growth and low filamentation. However, RPMI promotes moderate filamentation and growth of C. albicans (G). The peak of mycelium production appeared between 1.5 to 4.5h after inoculation of C. albicans O and between 1.5 to 6.0 and 7.5h for C. albicans G. the pH value of 7.4 appeared to be optimal for filamentation on MSB at 37°C for C. albicans. O (Oral pH slightly alkaline), While, pH of 4.4 was responsible for highest mycelia formation of C albicans G. (vaginal pH around 4.5) under same cultural conditions incubation temperature of 37°C was concomitant with the highest germ-tube formation by C. albicans O, on MSB at pH 7.4 while 34°C was optimum for filamentation by C. albicans G. on MSB at pH 4.4. These results indicated that the pattern of filamentation by C. albicans depends mainly on the yeast strain. The nutritional and cultural conditions control the route of yeast dimorphism. The two C. albicans strains (O and G) showed the same phenotypic switching when grown on solid media of MSB, RPMI, horse serum and blood agar base, in presence of 7%C02 (anaerobic) and in absence of 7%C02 (aerobic) conditions). However C. albicans G showed phenotypic switching on chocolate agar (feet appendages in presence of 7%C02 and normal growth in absence of CO2) while C. albicans O showed no switching under the same conditions

Keywords: Morphogenesis. Dimorphism. Gefm-tube. Filamentation. Phenotypic switching