YEAST NITROGEN BASE (W/O AMINO ACIDS AND AMMONIUM SULPHATE)

Yeast Nitrogen Base without Amino Acids and Ammonium Sulphate is used for classifying yeasts based on carbohydrate and amino acids requirements. This medium lacks the amino acids, histidine, methionine and tryptophan and also ammonium sulphate. Yeast Nitrogen Base is prepared as per the formulations of Guenter, which in turn is modification of Wickerham’s formulation. Wickerham used the following nitrogen sources – ammonium sulphate 1.0 gm/l, potassium nitrate 0.78 gm/l, urea 0.46 gm/l, asparagine 1.0 gm/l, peptone 1.32 gm/l. Yeasts grown on rich medium may carry a reserve of nitrogen in the form of proteins that may result in erroneous findings. To avoid this, 2 serial transfers in complete medium are recommended. After sufficient incubation, measure the growth turbid metrically at 660 nm using spectrophotometer and compare with control.

for isolation of dimorphic pathogenic fungi