Analysis of isoflavone glycoside-specific glucosidase produced by plant-derived lactic acid bacteria

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05437
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38050:Food sciences-related
• Research Institution: Niigata University
• Principal Investigator: JOH Toshio 新潟大学, 自然科学系, 教授 (00251794)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: イソフラボン / 乳酸菌 / β-グルコシダーゼ

Outline of Final Research Achievements

In this study, we used lactic acid bacteria strains with different isoflavone glycoside decomposition abilities and attempted to elucidate the reasons for the differences in glycoside decomposition abilities through analysis of β-glucosidase. When the enzyme activity of bacterial cells was measured using two types of substrates: a synthetic substrate and daidzin, an isoflavone glycoside, the low-decomposition strain showed activity only against the synthetic substrate, but the high-decomposition strain showed activity against daidzin. The results showed that the high-decomposition strain contained a isoflavone glycoside-specific enzyme. In addition, when examining the localization of enzymes in the two high-decomposition strains, it was found that both glycoside non-specific enzymes and glycoside-specific enzymes were present in the cell wall, and the non-specific enzyme was tightly bound to the cell wall. However, specific enzymes were found to be only loosely bound.

Free Research Field

食品科学

Academic Significance and Societal Importance of the Research Achievements

大豆中のイソフラボンの大部分は吸収されにくい配糖体として存在し、吸収率の向上には一部の腸内細菌が産生するβ-グルコシダーゼによる配糖体からの糖の分解が不可欠である。本研究においていくつかの乳酸菌株のβ-グルコシダーゼを調べたところ、イソフラボン配糖体の分解能の違いによらず一定の酵素活性を示すが、高いイソフラボン配糖体分解能を持つ乳酸菌株だけが配糖体特異的分解酵素を持つことを明らかにした。この知見は大豆イソフラボンの吸収効能を高める乳酸菌発酵食品の開発につながり、人々の健康増進に大きな貢献が期待できる成果である。