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Updated: Jun 26, 2025
Screening and Isolation of C-Glycoside-Cleaving Intestinal Bacteria
Published on: February 28, 2025
Flavonoids Biotransformation by Human Gut Bacterium Dorea sp. MRG-IFC3 Cell-Free Extract
Huynh Thi Ngoc Mi1, Heji Kim1, Jong Suk Lee2
1Metalloenzyme Research Group and Department of Plant Science and Technology, Chung-Ang University, Anseong 17546, Republic of Korea.
Abstract:
Human gut bacterium Dorea sp. MRG-IFC3 is unique in that it is capable of metabolizing puerarin, an isoflavone C-glycoside, whereas it shows broad substrate glycosidase activity for the various flavonoid O-glycosides. To address the question on the substrate specificity, as well as biochemical characteristics, cell-free biotransformation of flavonoid glycosides was performed under various conditions. The results showed that there are two different enzyme systems responsible for the metabolism of flavonoid C-glycosides and O-glycosides in the MRG-IFC3 strain. The system responsible for the conversion of puerarin was inducible and comprised of two enzymes. One enzyme oxidizes puerarin to 3"-oxo-puerarin and the other enzyme converts 3"-oxo-puearin to daidzein. The second enzyme was only active toward 3"-oxo-puerarin. The activity of puerarin conversion to daidzein was enhanced in the presence of Mn2+ and NAD+. It was concluded that the puerarin C-deglycosylation by Dorea sp. MRG-IFC3 possibly adopts the same biochemical mechanism as the strain PUE, a species of Dorea longicatena.
Insights
Dorea sp. MRG-IFC3 metabolizes puerarin (a C-glycoside) using a two-enzyme system. This gut bacterium also processes O-glycosides, indicating distinct enzymatic pathways for different flavonoid types.
Area of Science:
- Microbiology
- Biochemistry
- Enzymology
Background:
- Human gut bacterium Dorea sp. MRG-IFC3 exhibits unique metabolic capabilities.
- It can metabolize puerarin, an isoflavone C-glycoside.
- The bacterium also displays broad glycosidase activity towards flavonoid O-glycosides.
Purpose of the Study:
- To investigate the substrate specificity and biochemical characteristics of Dorea sp. MRG-IFC3's glycosidase activity.
- To elucidate the enzymatic mechanisms involved in the metabolism of C-glycosides and O-glycosides.
- To determine the specific enzymes responsible for puerarin metabolism.
Main Methods:
- Cell-free biotransformation of various flavonoid glycosides under diverse conditions.
- Enzyme activity assays to identify specific substrates and reaction products.
- Analysis of cofactor requirements and induction patterns for enzyme systems.
Main Results:
- Two distinct enzyme systems are responsible for flavonoid C-glycoside and O-glycoside metabolism in Dorea sp. MRG-IFC3.
- The puerarin metabolism pathway involves two inducible enzymes: one oxidizing puerarin to 3"-oxo-puerarin, and another converting it to daidzein.
- The second enzyme shows specific activity towards 3"-oxo-puerarin, and puerarin conversion is enhanced by Mn2+ and NAD+.
Conclusions:
- Dorea sp. MRG-IFC3 possesses separate enzymatic systems for C- and O-glycoside metabolism.
- The puerarin C-deglycosylation mechanism in Dorea sp. MRG-IFC3 is likely similar to that observed in Dorea longicatena strain PUE.
- This study clarifies the biochemical basis for puerarin metabolism in a human gut bacterium.
