P43: Metaproteome analysis of soybean proteins during the fermentation process of Meju, Korean traditional fermented soybean

Meju is a Korean traditional fermented soybean which has been used for soybean source and paste in Korea and also known as a source of bioactive peptides of soybean seeds. In this study, proteomics approach was applied to analyze change of soybean seed proteins and bioactive peptides during the fermentation process of Meju. Meju samples were taken at 0, 14, 28, 42, and 63 day-fermentation, and homogenized and fractionated to soluble (liquid) and solid fractions. LC-MS/MS analysis was performed with a LTQ-velos linear ion-trap mass spectrometer and proteins were identified by SEQUEST algorithm using the soybean protein database (44,642 proteins of Glycine max). Total 415 soybean proteins were identified during the whole fermentation process (96 from soluble fraction and 389 proteins from solid fraction). COG analysis indicated that proteins of COG G category (carbohydrate transport and metabolism) increased in the soluble fraction during fermentation. The increase in COG G was mainly caused by β-conglycinin, which is a seed storage protein and major source of bioactive peptides. Furthermore, some bioactive peptides originating from β-conglycinin were found to increase during the fermentation process. Our study revealed that proteomics is a useful tool to provide important information on changes in soybean seed proteins during the fermentation process, suggesting that Meju is an important source of useful bioactive peptides from soybean seeds.