Effect of licochalcone A on growth and properties of Streptococcus suis.
Streptococcus suis (S.suis) is an important emerging worldwide pig pathogen and zoonotic agent with rapid evolution of virulence and drug resistance. In this study, we wanted to investigate the effect of licochalcone A on growth and properties of Streptococcus suis. The antimicrobial activity of licochalcone A was tested by growth inhibition assay and the minimal inhibitory concentrations (MICs) also were determined. The effect of licochalcone A on S.suis biofilm formation was characterized by crystal violet staining. The effect of licochalcone A on suilysin secretion was evaluated by titration of hemolytic activity. To understand the antimicrobial effect, gene expression profile of S.suis treated by licochalcone A was analyzed by DNA microarray. Our results demonstrated that licochalcone A showed antimicrobial activity on S.suis with MICs of 4 µg/ml for S.suis serotype 2 strains and 8 µg/ml for S.suis serotype 7 strains. Biofilm formation was inhibited by 30-40% in the presence of licochalcone A (3 µg/ml) and suilysin secretion was also significantly inhibited in the presence of licochalcone A (1.5 µg/ml). The gene expression profile of S.suis in the presence of licochalcone A showed that 132 genes were differentially regulated, and we analyzed the regulated genes in the aspect of the bacterial cell cycle control. Among the deregulated genes, the genes responsible for the mass doubling was increased expression, but the genes responsible for DNA replication and cell division were inhibited the expression. So, we think the regulation of the cell cycle genes might provide a mechanistic understanding of licochalcone A mediated antimicrobial effect against S.suis.
State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China.
Huaijie
H
Hao
Wenjia
W
Hui
Peng
P
Liu
Qingyu
Q
Lv
Xiaotao
X
Zeng
Hua
H
Jiang
Yanzi
Y
Wang
Xin
X
Zheng
Yuling
Y
Zheng
Jianchun
J
Li
Xuyu
X
Zhou
Yongqiang
Y
Jiang
D018441:Biofilms / Q000187:drug effects; D047188:Chalcones / Q000494:pharmacology*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics; D006460:Hemolysin Proteins / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D020411:Oligonucleotide Array Sequence Analysis; D017011:Streptococcus suis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development* / Q000502:physiology
D047188:Chalcones; D006460:Hemolysin Proteins; C104760:suilysin; C070840:licochalcone A