Peptide hydrolysate supplements in mammalian cell cultures provide enhanced growth and productivity. The objective of this study was to compare the bioactivity of ten different commercially available hydrolysates from plant, microbial, and animal sources. The peptide hydrolysates were tested as supplements to cultures of Chinese hamster ovary (CHO) cells that produce human beta interferon (-IFN). A soy hydrolysate was shown to support high cell growth but not protein productivity compared to an animal component hydrolysate (Primatone RL). On the other hand, a yeast hydrolysate showed lower cell growth, but comparable productivity of the recombinant protein. Glycosylation analysis showed that the glycan profile of -IFN produced in yeast hydrolysate supplemented cultures was equivalent to that from Primatone RL-supplemented cultures. Fractionation of the yeast hydrolysate and Primatone RL produced a similar protein-assayed pattern except for one extra peak at around 1 kDa in the Primatone RL profile. A fraction taken at a molecular weight range of 1.5-1.7 kDa showed the highest growth promoting activity in both samples. However, four other fractions in yeast hydrolysate and two in Primatone RL at lower molecular weights showed some growth promoting activity. In conclusion, the yeast hydrolysates provided a good alternative to the animal sourced Primatone RL for high productivity of -IFN from CHO cells with equivalent glycosylation. (c) 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:584-593, 2014