A major component of the horns is protein. Peptones are defined as protein hydrolysates. The potential use of ram horn peptone (RHP) as a nitrogen source for glycerol production by Saccharomyces cerevisiae was studied. For this purpose, first, RHP was produced. Ram horns were hydrolyzed by treating with acids (6 N H2SO4 and 6 N HCl) and neutralizing the solutions. The amounts of protein, nitrogen, ash, some minerals, total sugars, total lipids and amino acids of the RHP were determined. The RHP was compared with a bacto-tryptone from casein and other peptones. With the addition of RHP to, the fermentation medium with a final concentration of 4% (optimal concentration), the glycerol value for 4 days reached a maximum value (8.5 g l(-1)), which is 25% higher than that of the bacto-tryptone (6.8 g l(-1)), 32% higher than that of bacto-peptone (6.4 g l(-1)) and 49% higher than that of fish peptone (5.7 g l(-1)). The results show that RHP can be utilized as a peptone and may be a valuable supplement in biotechnology. (C) 2003 Elsevier Ltd. All rights reserved.