Antimicrobial Activity of Extracts from Different Parts of Lonicera japonica Thunb. and Their Antibacterial Properties against Alicyclobacillus acidoterrestris

This study investigated the bioactive substance contents within extracts derived from different parts of Lonicera japonica Thunb. and assessed their bacterial inhibitory activities against 12 test strains. Initially, the concentrations of total phenols, total flavonoids, and chlorogenic acid were determined in Lonicera japonica leaves, Lonicerae japonica Flos, and Lonicera japonica caulis. Subsequently, the bacterial inhibition profiles of their extracts against 12 test strains were analyzed. Building upon this analysis, the effects of Lonicerae japonica Flos and Lonicera japonica leaves extracts on minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), growth curve, biofilm formation, and cell morphology of Alicyclobacillus acidoterrestris were further investigated. Results revealed that the concentrations of total phenols, total flavonoids, and chlorogenic acid in L. japonica leaves and L. japonica Flos were significantly higher than those from L. japonica caulis (P<0.05). Moreover, the total flavonoids content in L. japonica leaves was notably higher than that in L. japonica Flos (P<0.05). Three extracts exhibited varying degrees of bacteriostatic effects against A. acidoterrestris, Staphylococcus aureus, Streptococcus agalactiae, Listeria monocytogenes, Bacillus subtilis, Escherichia coli and Salmonella. Notably, extracts of L. japonica leaves and L. japonica Flos displayed superior bacteriostatic effects compared to L. japonica caulis. Extracts of L. japonica leaves and L. japonica Flos exhibited the most significant bacteriostatic effects against A. acidoterrestris, with MIC of 3.91 mg/mL and MBC of 31.25 mg/mL. Furthermore, extracts from L. japonica leaves and L. japonica Flos effectively inhibited the growth and biofilm formation of A. acidoterrestris, causing disruptions to their organism morphology. Notably, the inhibitory effects were augmented with the increase of extract concentrations. This study lays a robust foundation for understanding the mechanisms behind L. japonica inhibition of A. acidoterrestris and offers insights for developing safe and efficient new food bacteriostatic agents.