Spent brewery yeast sludge as a single nitrogen source for fibrinolytic enzyme production of Virgibacillus sp. SK37

The objectives of this study were to investigate the suitable food industrial byproducts and conditions affecting proteinase production of Virgibacillus sp. SK37 as well as to evaluate fibrinolytic activity of secreted proteinases. Among 5 food industrial wastes including soybean pomace, rice bran, mungbean protein, spent brewery yeast sludge (Ys), and fish sauce sludge, Ys was the best nitrogen source for proteinase production from Virgibacillus sp. SK37. The highest level of proteinase production was obtained in the medium containing 1% Ys, 2.5% NaCl, pH 7.5 at 40°C, which was about 1.7 times higher than the commercial yeast extract medium. Virgibacillus sp. SK37 proteinases completely hydrolyzed fibrinogen within 50 min with Aα-chain being the first target and followed by Bβ- and Γ-chains. Virgibacillus sp. SK37 could be a potential source of fibrinolytic enzyme that can be developed as a functional food ingredient.