Optimal concentration of ammonium ion in a minimal synthetic medium for the growth of Candida albicans.

Candida albicans strain B 311-10 with and without starvation was cultivated in the minimal synthetic medium of Shepherd et al., modified without biotin, amino acids, low glucose concentration and with decreasing amounts of (NH4)2SO4, to determine the optimal growth requirement for this strain. All the experiments were carried out under sterile conditions at 25 degrees C in a thermostat with initial O.D.s (675 nm) of 0.500 and 0.100. Cell growth was generally monitored everyday for six days with a spectrophotometer by determining the absorbance of the cultures at 675 nm. All the experiments were repeated three times and a statistical analysis of the data with a probability of 99% and 1% of error was performed to confirm the validity of the results. Best growth was obtained with starved cells at an initial O.D. of 0.100 and with a 0.1 g/L concentration of (NH4)2SO4. At this concentration, the growth of C. albicans B 311-10 was best between the first and the fourth day with the maximum at the third day. With (NH4)2SO4 concentrations of 0.05 and 0.5 g/L, cell growth was the same.