Identification of the antibacterial action mechanism of diterpenoids through transcriptome profiling.

Effective antibacterial substances of have anti-biofilm and bactericidal activity to the oral pathogen . In this study, three compounds extracted from were identified as acanthoic acid, continentalic acid, and kaurenoic acid by NMR and were further investigated how these diterpenoids affect the physiology of the . When was exposed to individual or mixed fraction of diterpenoids, severe growth defects and unique morphology were observed. The proportion of unsaturated fatty acids in the cell membrane was increased compared to that of saturated fatty acids in the presence of diterpenoids. Genome-wide gene expression profiles with RNA-seq were compared to reveal the mode of action of diterpenoids. commonly enhanced the expression of 176 genes in the presence of the individual diterpenoids, whereas the expression of 232 genes was considerably reduced. The diterpenoid treatment modulated the expression of genes or operon(s) involved in cell membrane synthesis, cell division, and carbohydrate metabolism of . Collectively, these findings provide novel insights into the antibacterial effect of diterpenoids to control infection, which causes human dental caries.