Enzyme Activities and Physiological Functionalities of Lactic Acid Bacteria Isolated from Korean Meju (fermented soybean block)

Meju is a naturally fermented soybean block and the main ingredient of deonjang (Korean soybean paste). Microorganisms in meju are sources of enzymes in soybean fermentation. Three kinds of Korean traditional meju were selected and their counts of microorganisms were evaluated. The levels of total aerobic bacteria, lactic acid bacteria, and yeasts and molds were 10 7 –10 8 cfu/g, 10 6 –10 7 cfu/g and 10 7 –10 8 cfu/g, respectively in the three meju samples. We isolated three kinds of dominant lactic acid bacteria from the mejus and they were identified as Leuconostoc mesenteroides (98%), Lactobacillus plantarum (99%) , and Lactococcus lactis (98%). Enzyme activities and functionalities of three lactic acid bacteria were investigated. Protease, lipase and α‐amylase activities were detected in three lactic acid bacteria. Lactococcus lactis showed relatively higher activities than other two lactic acid bacteria. Leuconostoc mesenteroides, Lactobacillus plantarum and Lactococcus lactis showed 45%, 48% and 60% of antioxidative activity to α, α‐diphenyl‐β‐picryhydrazyl (DPPH), and exhibited 45%, 67% and 70% of inhibitory effects in HT‐29 human colon cancer cells. These results indicate that three lactic acid bacteria isolated from the meju, especially, Lactococcus lactis are very applicable to soybean paste industry. This research is supported by the National Institute of Agricultural Science and Technology, Rural Development Administration, Korea.