A CELL-CULTURE MODEL TO IDENTIFY BIOLOGICALLY-ACTIVE PEPTIDES GENERATED BY BACTERIAL HYDROLYSIS OF CASEIN

Consumption of fermented dairy foods has been linked to reduced incide nce of colon cancer in population groups. Recently, biologically activ e compounds have been isolated from these products. Bacterial proteina ses, produced by dairy starter cultures, generate a variety of peptide s from casein. Some of these casein-derived peptides are likely to alt er intestinal cell kinetics. Effects on colon cell kinetics because of the presence of casein-derived peptides may be a mechanism through wh ich fermented dairy foods reduce the risk of colon cancer. We have use d two intestinal cell lines (IEC-6 cells, derived from normal rat inte stine, and Caco-2 cells, derived from human colon adenocarcinoma) to i dentify casein peptides that affect intestinal cell kinetics. Cell cul ture media containing casein were inoculated with three commercial sta rter cultures and incubated for 4, 8, or 24 h. The bacteria-conditione d media were then filter-sterilized and incubated with the intestinal cells for 6 or 24 h. Rates of [H-3]thymidine incorporation and cell cy cle kinetics determined by flow cytometry were affected by the culture -modified media in both cell lines. The IEC-6 cells tended to reduce, and Caco-2 cells to increase, rates of cell division after exposure to the media. Intestinal cell response varied among the starter cultures . The results support the use of intestinal cell cultures to identify casein peptides generated by dairy starter cultures, which affect inte stinal cell kinetics.