Biosynthesis of antibacterial compound against multidrug resistant foodborne pathogens by Phomopsis sp XP-8

Multi-drug resistance of foodborne pathogens has been greatly highlighted in food safety and caused a significant challenge for the development of new antibiotics and safe preservatives. The ethanol extract of Phomopsis sp. XP-8 broth showed significant inhibitory effects on multi-drug resistance of foodborne pathogens. After purification with thin-layer chromatography and liquid chromatographic analysis, the antibacterial compound was identified as methyl quercetin according to FTIR spectrum analysis and ESI-Q-TOF-MS analysis. Via substrate-feeding experiments, the mass flow for the biosynthesis of methyl quercetin was defined as (starting from glucose to phenylalanine): cinnamic acid, p-coumaric acid, quercetin, and methyl quercetin. The study revealed the capability of methyl quercetin to inhibit foodborne multi-drug resistant Escherichia coli, Staphylococcus aureus, and Salmonella shubra, as well as the capability of Phomopsis sp. XP-8 to produce methyl quercetin, showing potential application in food control.