Safety evaluation, hydrolysis activity of Kluyveromyces marxianus JY-1 and its application to obtain immunomodulatory peptide from bovine casein

Abstract

Except in vitro enzymolysis, there are few studies on the production of casein-derived immunomodulatory peptides by microbial fermentation technology. In this study, the ability of a strain of Kluyveromyces marxianus JY-1 isolated from traditional fermented milk in Xinjiang District (China) to release casein-derived immunomodulatory peptides was evaluated. Results showed that this strain was safe and with high protease activity, which could highly hydrolyze casein. The hydrolysate of casein hydrolyzed by Kluyveromyces marxianus JY-1 could promote the proliferation of RAW264.7 macrophages and the production of cytokines (IL-6, IL-1β, and TNF-α) compared with the control group, showing obvious immunomodulatory activity. A nanoscale liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (Nano LC-Q-TOF-MS/MS) was used to determine the amino acid sequences of bioactive peptides in casein hydrolysate of Kluyveromyces marxianus. According to the structural characteristics of immunomodulatory peptides, 3 peptides (HPHPHLSF, PFPEVFG, and SPAQILQW) with immunomodulatory activity were selected from 55 identified peptides by using in silico methods. This study demonstrates that Kluyveromyces marxianus JY-1 has a wide range of potential applications in the production of immunomodulatory peptides from casein and other food proteins.