Inactivation effect of extracts of gardenia fruit, licorice and Torilis japonica fruit against Bacillus spores

For the development of natural antimicrobial agents targeting Bacillus subtilis spores, this study compared the inactivation effects of ethanol extracts from gardenia fruit, licorice, and Torilis japonica fruit against those of commercial antibacterial agents. A 0.01% (w/w) concentration of polylysine with surfactant property exhibited a sporicidal effect, reducing Bacillus spore concentrations by 2 log CFU/g. Ethanol extracts of gardenia fruit at 0.05% and Torilis japonica fruit at 0.01% concentration showed significant bactericidal effects on both Bacillus spores and vegetative cells, achieving a reduction of 2–4 log CFU/g within 2–48 h. Licorice ethanol extract at 0.005% concentration displayed in a 2–4 log CFU/g after 24–48 h coinciding with spore conversion to vegetative cells. A combination of ethanol extracts of 0.05% gardenia fruit and 0.005% licorice produced a bactericidal effect, resulting in a 2–5 log CFU/g reduction over 48 h of growth.