In order to evaluate the blood pressure-lowering peptide Tyr-Pro (YP) derived from casein, we wanted to develop an efficient fermentation method. Therefore, we chose to use a jar fermentor for this purpose. Strains with an excellent antihypertensive peptide-releasing ability from casein were selected from basidiomycete fungi that grow well in milk under shaking conditions accompanied by physical stimulation. Among them, the white-rot fungus Peniophora sp., which is suited for growth only in cow’s milk or low-fat milk under vigorous shaking conditions, was found to release peptides and amino acids from milk. When comparing the growth in cow’s milk and low-fat milk, there was no particular difference in the growth of mycelia between the two, but this fungus tended to preferentially consume lactose under low-fat conditions. The fermented milk exhibited good production of the target peptide YP. The expression of many genes encoding proteolytic enzymes, such as aminopeptidases and carboxypeptidases, was observed during the milk fermentation. Furthermore, this fungus showed good growth in a jar fermentor culture using only cow’s milk or low-fat milk, which enabled the efficient production of YP and ACE-inhibitory activity. At this time, it was more effective to use cow’s milk than low-fat milk. These results suggest that Peniophora sp. could be potentially useful in the production of the functional YP peptide from milk.
Proteolytic Enzymes in Human and Cow's Milk