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.