Finally, the cell suspension was plated on to yeast synthetic
drop-out media which lacks uracil (yeast nitrogen base without
amino acids and ammonium sulphate, 1.7 g/l; ammonium sulphate,
5 g/l; casein hydrolysate, 5 g/l; tryptophan, 20 mg/l; agar,
20 g/l) and incubated at 28 C for 2 day