Purpose: Garlic-derived organosulfur compounds are found to be highly effective antimicrobial compounds against different foodborne pathogens, resulting in less antimicrobial resistance.
Methods: We used high-throughput whole-transcriptome sequencing (RNA-seq) and vibrational spectroscopy to characterize and fingerprint C. sakazakii injury under treatment of two garlic -derived organosulfur compounds (diallyl sulfide and ajoene).
Results: Both diallyl sulfide and ajoene are highly effective in inactivating C. sakazakii. RNA-seq analyses showed that the bacterial response to ajoene differed from the response to diallyl sulfide. Specifically, ajoene caused downregulation of motility-related genes, while diallyl sulfide treatment caused an increased expression of cell wall synthesis genes. Confocal micro-Raman spectroscopy revealed that the two compounds appear to have the same phase I antimicrobial mechanism of binding to thiol-containing proteins/enzymes in bacterial cells generating a disulfide stretching band but different phase II antimicrobial mechanisms, showing alterations in the secondary structures of proteins in two different ways. Diallyl sulfide primarily altered the α-helix and β-sheet, as reflected in changes in amide I, while ajoene altered the structures containing phenylalanine and tyrosine. Scanning electron microscopy confirmed cell injury, showing significant morphological variations in cells following treatments by these two compounds.
Significance: Findings from this study aid in the development of effective intervention strategies to reduce the risk of C. sakazakii contamination in the food production environment and on food contact surfaces, reducing the risks to susceptible consumers.