Amino acids and Vitamins-The  importance  of  amino acids and vitamins in  human health is well-recognized. Several microbes have been used for their productions which are biologically suitable. Yeast is one of the best  sources of the vitamin B complex. A number of preparations of high  potency  vitamin B-complex  made  from dried  yeast and yeast extracts are available in the market. Riboflavin, one of the B-group vitamins, is produced from the yeast Eremothecium ashbyii. Ergosterol, the  precursor  of vitamin D  is  synthesized' by  a number of  moulds and yeasts.  p-carotene  is  produced  commercially  by fermentation  using  the  fimgus Rhodotorula.