Identification of the antibacterial action mechanism of diterpenoids through transcriptome profiling

Keumok Moon; Sungmin Hwang; Hyeon-Jeong Lee; Eunhye Jo; Jeong Nam Kim; Jaeho Cha

doi:10.3389/fmicb.2022.945023

Identification of the antibacterial action mechanism of diterpenoids through transcriptome profiling

Front Microbiol. 2022 Jul 26:13:945023. doi: 10.3389/fmicb.2022.945023. eCollection 2022.

Authors

Keumok Moon¹, Sungmin Hwang², Hyeon-Jeong Lee³, Eunhye Jo³, Jeong Nam Kim^{3

4}, Jaeho Cha^{1

3

4}

Affiliations

¹ Microbiological Resource Research Institute, Pusan National University, Busan, South Korea.
² Clean Energy Research Center, Korea Institute of Science and Technology, Seoul, South Korea.
³ Department of Integrated Biological Science, College of Natural Sciences, Pusan National University, Busan, South Korea.
⁴ Department of Microbiology, College of Natural Sciences, Pusan National University, Busan, South Korea.

Abstract

Effective antibacterial substances of Aralia continentalis have anti-biofilm and bactericidal activity to the oral pathogen Streptococcus mutans. In this study, three compounds extracted from A. continentalis were identified as acanthoic acid, continentalic acid, and kaurenoic acid by NMR and were further investigated how these diterpenoids affect the physiology of the S. mutans. When S. mutans 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. Streptococcus mutans 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 S. mutans. Collectively, these findings provide novel insights into the antibacterial effect of diterpenoids to control S. mutans infection, which causes human dental caries.

Keywords: Aralia continentalis; Streptococcus mutans; antibacterial activity; diterpenoids; transcriptome analysis.