Green huajiao (Zanthoxylum schinifolium) essential oil (GHJEO) is a natural medicinal and flavoring essential oil. GHJEO has been reported to show good antibacterial activity as a promising alternative to chemical food preservatives in the food industry. However, the antibacterial mechanism of GHJEO has rarely been reported. In this study, we analyzed the antibacterial mechanism of GHJEO against Bacillus cereus at the physicochemical, morphological and metabolic levels. GHJEO contained many previously reported antibacterial components. The MIC and MBC of GHJEO against B. cereus were determined to be 2.0 and 4.0 mg/mL, respectively. We found that GHJEO could destroy the cell wall and membrane of Bacillus cereus, causing cytoplasmic leakage. In addition, GHJEO at a subinhibitory concentration (0.5 MIC) could cause significant metabolic changes of B. cereus. Further bioinformatics analysis revealed that GHJEO could cause cell membrane damage, energy metabolism disorders, and amino acid metabolism disorders. The results of this study may be beneficial for the development and application of GHJEO in food safety.

In this study, the pure culture method combined with metagenomic analysis was used to investigate the evolutionary relationship of 66 strains of Bacillus isolated from Pixian broad bean paste. The enzyme activities and antibiotic resistance of the selected representative strains were further analyzed. Totally 24 Bacillus strains were identified by metagenomics and were classified into 13 species according to full-length 16S rDNA gene sequences. As the salt content rose, the protease-producing and amylase-producing abilities of the 29 representative strains decreased. All the strains were susceptible to neomycin, but their sensitivity to 11 other antibiotics tested was largely different. Among the 12 antibiotics, the incidence of ampicillin resistance was the highest (66%). Our findings motivate the future utilization of the Bacillus strains from Pixian broad bean paste.