Antimicrobial activity of magnolol against Bacillus cereus and its application as food preservative

Abstract

The aim of this study was to explore the antibacterial properties and mechanism of magnolol against Bacillus cereus. Our findings demonstrated that magnolol exhibited potent antimicrobial activity against B. cereus, with minimum inhibitory concentrations (MICs) of 2 μg/mL. Additionally, magnolol could inhibit spore germination and biofilm formation in a dose-dependent manner. Electron microscopy and membrane potential analysis indicated that the cytomembranes were disrupted, resulting in leakage of cellular contents. Transcriptomic profiling showed that magnolol treatment (1/2 × MIC) resulted in 585 differentially expressed genes (DEGs), including 295 down-regulated and 290 up-regulated genes. Bioinformatic analysis indicated that magnolol affected many potential cellular responses, including cellular metabolic process, locomotion, oxidative stress, and cell membranes. The pathway analysis revealed that DEGs mainly associated with flagellar assembly, bacterial chemotaxis, amino acids, and energy metabolism. Moreover, magnolol obviously reduced the amount of B. cereus in boiled rice and beef at 4 °C storage. These results provided insights into the molecular mechanism of magnolol against B. cereus and suggested that magnolol might be a promising natural antimicrobial agent for controlling the B. cereus in foods. Industrial relevanceBacillus cereus is considered as an important foodborne pathogenic microorganism that can exist as vegetative cells, spores, and biofilm in various food-processing environment, posing a big challenge for the food industry. Magnolol is a natural compound with potent antimicrobial activity against various pathogens and has been certified as safe by food safety organizations. Consequently, magnolol holds great promise as a natural antimicrobial agent for controlling B. cereus contaminations in foods.