RESUMO
Evidence suggests that small noncoding RNAs (sRNAs) are involved in the complex regulatory networks governing biofilm formation. Few studies have investigated the role of sRNAs in Streptococcus mutans (S. mutans). In the present study, the association between sRNA and biofilm formation in S. mutans was explored. sRNAs that are differentially expressed in the biofilm and planktonic states of this bacterium were identified by quantitative real-time PCR (qRT-PCR). Confocal laser scanning microscopy was used to investigate the characteristics of biofilm formation in a standard strain of S. mutans (UA159, ATCC 700610) and ten clinical strains. Bioinformatics analyses were employed to predict and examine potential sRNA regulatory pathways. The results showed that sRNA0426 has a strong positive relationship with dynamic biofilm formation. Moreover, sRNA0426 expression was positively correlated with exopolysaccharide (EPS) production. Bioinformatics analyses showed that sRNA0426 is involved in biofilm formation such as metabolic pathways, especially carbon metabolism. Five target mRNAs (GtfB, GtfC, GtfD, ComE, and CcpA) involved in the synthesis of EPS were selected for further evaluation; the expression levels of three of these mRNAs (GtfB, GtfC, and CcpA) were positively correlated with sRNA0426 expression levels, and the expression level of one (ComE) was negatively correlated. In conclusion, the results suggested that sRNA0426 may play an important and positive role in the biofilm formation of S. mutans and provide novel insight into the S. mutans biofilm regulatory network.
Assuntos
Polissacarídeos Bacterianos/biossíntese , RNA Bacteriano/metabolismo , Pequeno RNA não Traduzido/metabolismo , Streptococcus mutans/genética , Streptococcus mutans/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes , Regulação Bacteriana da Expressão Gênica , Redes Reguladoras de Genes , Redes e Vias Metabólicas , Conformação de Ácido Nucleico , Polissacarídeos Bacterianos/genética , RNA Bacteriano/química , RNA Bacteriano/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Pequeno RNA não Traduzido/química , Pequeno RNA não Traduzido/genética , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Streptococcus mutans and Candida albicans are often isolated from plaques associated with early childhood caries. However, there are limited studies examining how these microorganisms interact with one another and how best to manage them. Recent studies have shown that curcumin (CUR), a natural compound, has the potential to independently control both of these microorganisms. The purpose of this study was to investigate how S. mutans and C. albicans respond in mono- and dual-species biofilms challenged with CUR. Quantitative biofilm biomass and viability were first evaluated and supported by live-dead PCR to assess biofilm composition. Confocal laser scanning microscopy (CLSM) was used to evaluate the exopolysaccharide (EPS) content and thickness of the biofilms, and the structure of the biofilms and morphology of the cells were observed by scanning electron microscopy (SEM). Quantitative real-time PCR (qRT-PCR) was applied to assess relative gene expression. The 50% minimum biofilm eradication concentration (MBEC50 ) of CUR against S. mutans and C. albicans was 0.5 mM. The biomass and viability decreased after treatment with CUR both in dual-species biofilms and in mono-species biofilm. CUR inhibited S. mutans and C. albicans in both mono- and dual-species biofilms. Streptococcus mutans was more sensitive to CUR in dual-species biofilm than in mono-species biofilms, whereas C. albicans was less sensitive in dual-species biofilms. EPS production was decreased by CUR in both mono- and dual-species biofilms, which coincided with the downregulation of glucosyltransferase and quorum sensing-related gene expression of S. mutans. In C. albicans, the agglutinin-like sequence family of C. albicans was also downregulated in dual-species biofilms. Collectively, these data show the potential benefit of using a natural antimicrobial, CUR, to control caries-related dual-species plaque biofilms.
