Acteria, though its antimicrobial mechanism was not well elucidated. One possible

Acteria, though its antimicrobial mechanism was not well elucidated. One possible mechanism is that licochalcone A could inhibit the bacterial respiratory electron transport chain at the site between Coenzyme Q and cytochrome c [26]. In this study, we tried to investigate the antimicrobial mechanism of licochalcone A in the aspect of bacterial cell cycle control. How organisms adjust their cell cycle dynamics to compensate for changes in nutritional conditions is an important outstanding question in bacterial physiology. Nutrient availability and metabolic status are coordinated with cell growth, chromosome Mirin cost replication and cell division. The gene expression profile of S.suis treated by licochalcone A showed that S.suis genes responsible for amino acid transport and anabolism of amino acid were up-regulated significantly and genes for catabolism of amino acid were down-regulated. These results indicated that S.suis cells 16574785 might be in the status of amino acid starvation, while amino acid starvation directly inhibits replication initiation through the production of guanosine tetraphosphate and guanosine pentaphosphate. On the other hand, S.suis genes for celldivision were also been down-regulated. Taken together, we supposed that licochalcone A might inhibit the growth of S.suis by controlling the replication initiation and cell division through the amino acid metabolism.ConclusionsIn this study, we tried to investigate the effect of licochalcone A on growth and properties of Streptococcus suis, an important emerging worldwide pig pathogen and zoonotic agent with rapid evolution of virulence and drug resistance. Our results demonstrated that licochalcone A could effectively inhibit the growth, biofilm formation and suilysin secretion of S.suis. Besides, we put forward a hypothesis to elucidate the antimicrobial mechanism of licochalcone A in the aspect of bacterial cell cycle control. Namely, licochalcone A might inhibit the growth of S.suis by controlling the replication initiation and cell division through amino acid metabolism. Our results demonstrated that licochalcone A might be a useful compound for the development of prevention and therapy agent for S.suis infection.Materials and Methods Ethics statementAll the experiments in the paper were conducted under the supervision of the Institutional Review Board of the Academy of Military Medical 16574785 might be in the status of amino acid starvation, while amino acid starvation directly inhibits replication initiation through the production of guanosine tetraphosphate and guanosine pentaphosphate. On the other hand, S.suis genes for celldivision were also been down-regulated. Taken together, we supposed that licochalcone A might inhibit the growth of S.suis by controlling the replication initiation and cell division through the amino acid metabolism.ConclusionsIn this study, we tried to investigate the effect of licochalcone A on growth and properties of Streptococcus suis, an important emerging worldwide pig pathogen and zoonotic agent with rapid evolution of virulence and drug resistance. Our results demonstrated that licochalcone A could effectively inhibit the growth, biofilm formation and suilysin secretion of S.suis. Besides, we put forward a hypothesis to elucidate the antimicrobial mechanism of licochalcone A in the aspect of bacterial cell cycle control. Namely, licochalcone A might inhibit the growth of S.suis by controlling the replication initiation and cell division through amino acid metabolism. Our results demonstrated that licochalcone A might be a useful compound for the development of prevention and therapy agent for S.suis infection.Materials and Methods Ethics statementAll the experiments in the paper were conducted under the supervision of the Institutional Review Board of the Academy of Military Medical 23727046 Sciences. All the bacterial isolates were isolated previously and kindly provided by the hospital, Institutes or Academy. No samples were collected from patients directly in this study and therefore the study was exempt from obtaining informed consent. All relevant ethical safeguards have been met in the experiments.Streptococcus suis and culture conditionsS.suis strain 05ZYH33 (previously isolated from an STSS patient with S.suis infection) and other S.suis strains (listed in Table 1) were used in this study. The microorganism was maintained on Columbia blood agar (BioMerieux) supplemented with 5 sheepInhibition Effect of Licochalcone A on S.suisTable 2. List of significant regulated genes of S.suis in the presence of licochalcone A.Gene IDGene nameCOGFold change*AnnotationEnergy production and conversion 05SSU1205 05SSU0280 C C 2.23 211.97 Aconitase A NAD-dependent aldehyde dehydrogenaseCell division and chromosome partitioning 05SSU0417 05SSU0479 gpsB D D 22.06 22.91 Cell division initiation protein Actin-like ATPase involved in cell divisionAmino acid transport and metabolism 05SSU0252 05SSU07.