Screening and Isolation of C-Glycoside-Cleaving Intestinal Bacteria

C-glycosides are commonly found in medicinal plants and exhibit extensive structural diversity along with various bioactivities, including antibacterial, anti-inflammatory, antiviral, antioxidant, and antineoplastic activities. In C-glycosides, the anomeric carbon of the sugar moiety is directly connected to an aglycone through carbon-carbon bonding. Compared with O-glycosides, C-glycosides are structurally stable and resistant to acids and enzymes. Consequently, they are typically unbreakable, resulting in poor absorbability and low bioavailability. Interestingly, some intestinal bacteria can cleave C-C glycosidic bonds, providing a specific and environmentally friendly biological approach to degrade C-glycosides. In this study, a set of standard operating procedures (SOPs) was developed for screening intestinal bacteria capable of cleaving C-C glycosidic bonds based on the biotransformation model of natural compounds. The SOPs include the preparation and enrichment of intestinal bacteria, activity-oriented screening, and activity validation in a low-carbon source medium. This methodology provides a foundational reference for researchers aiming to isolate and study these specialized functional bacteria.