Proposing sequences for peptides derived from whey fermentation with potential bioactive sites

In fed-batch fermentation by Kluyveromyces marxianus var. marxianus, whey-soluble proteins were converted into oligopeptides. To assess whether bioactive peptides could be produced during whey fermentation, K. marxianus was cultured in batch in deproteinized media containing 5 or 15% (wt/vol) dehydrated whey for 20 h and then was in fed-batch mode for 50 h. After harvesting the biomass (25,000 x g, 15 min), at 6-h intervals, the wort was analyzed to determine protein consumption and oligopeptide production by HPLC. The proteins in the wort showed an oscillatory degradation with a constant increase in the production of oligopeptides. Four major peaks were collected and were analyzed by API mass spectroscopy. Sequences of fermented peptides were compared with sequences of known bioactive peptides. On the basis of their molecular weights, two amino acid sequences were proposed. The presence of sites containing the peptide sequence of beta-lactorphin (YLLF) suggests that these oligopeptides may have antihypertensive properties.