Improving the antioxidant and antibacterial activities of fermented Bletilla striata with Fusarium avenaceum and Fusarium oxysporum

• Bletilla striata was processed by pure strain fermentation for the first time.
• Fusarium avenaceum and Fusarium oxysporum might be effective in B. striata fermentation processing.
• UV–vis, FT-IR, and NMR spectra were effective in characterization of fermented B. striata.

The tubers of Bletilla striata were fermented with Fusarium avenaceum and Fusarium oxysporum. The total phenolic contents (TPCs) and antioxidant and antibacterial activities of the extracts from the fermented products were measured. Additionally, the extracts of both F. avenaceum and F. oxysporum fermented B. striata (FBS) were characterized by UV–vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. The results showed that the F. avenaceum and F. oxysporum FBSs possessed higher TPCs and exhibited stronger antioxidant and antibacterial activities (Bacillus subtilis) in comparison with original material not co-fermented with microorganisms. Chemical characterization of the two extracts with UV–vis, FT-IR, and 1H NMR implied that some of the phenolic glycosides may be deglycosylated and that bibenzyl compounds and saccharides may be metabolized in both FBS systems. Microbial fermentation enhances the TPC as well as the antioxidant and antibacterial activities of B. striata. The present study suggests that F. avenaceum and F. oxysporum fermentations were effective in B. striata processing.