RESUMEN
Streptococcus mutans, an agent of dental caries, was tested for growth in the presence or absence of manganese (Mn), since studies have linked Mn levels with cariogenic potential. Seven S. mutans serotype c strains were grown in chemically defined medium under different atmospheric conditions: 5% CO2, O2-enriched 5% CO2 (shaking) and anaerobic. There was significant strain variability with respect to Mn requirements under the various conditions tested. Both sucrose-dependent and sucrose-independent biofilm growth by strain UA159 were affected by the absence of Mn. S. mutans strains show highly variable responses to both high and low Mn concentrations.
Asunto(s)
Biopelículas/efectos de los fármacos , Manganeso/farmacología , Streptococcus mutans/efectos de los fármacos , Oligoelementos/farmacología , Biopelículas/crecimiento & desarrollo , Placa Dental/química , Placa Dental/microbiología , Procesamiento de Imagen Asistido por Computador , Sacarosa/farmacología , Edulcorantes/farmacologíaRESUMEN
BACKGROUND/AIMS: Studies of trace metals in drinking water and tooth enamel have suggested a caries-promoting potential for manganese (Mn). Additionally, Mn has been shown to be essential for the expression of mutans streptococci virulence factors such as the glucan-binding lectin (GBL) of Streptococcus sobrinus. The Streptococcus mutans glucan-binding protein (Gbp) GbpC is the functional analogue of the S. sobrinus GBL. S. mutans Gbps have been shown to contribute to biofilm architecture and virulence. This study was undertaken to examine the effects of Mn on the transcription of genes encoding S. mutans Gbps, including gbpC, along with other critical S. mutans virulence genes. METHODS: Microarray analyses suggested the potential for an Mn effect on Gbp genes. Further investigation of the Mn effects on selected genes was undertaken by performing Northern blots, Western blots, and RT-PCR under conditions of planktonic and biofilm growth in Mn-depleted media or in media containing 50 mircoM Mn. RESULTS: Mn resulted in increased expression of gbpC and gtfB, and decreased expression of wapA, in both planktonic and biofilm cultures. The expression levels of gbpA and gbpD were also decreased in the presence of Mn, but only in biofilms. The expression of gtfC was increased in the presence of Mn only in planktonic cultures. The spaP gene was expressed more highly in Mn-supplemented planktonic cultures but less in Mn-supplemented biofilms. CONCLUSION: Mn availability affects the expression of multiple S. mutans genes involved in adhesion and biofilm formation. Furthermore, these effects depend on the growth state of the organism.
Asunto(s)
Cariogénicos/farmacología , Expresión Génica/efectos de los fármacos , Manganeso/farmacología , Streptococcus mutans/efectos de los fármacos , Oligoelementos/farmacología , Animales , Proteínas Bacterianas/efectos de los fármacos , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Proteínas Portadoras/efectos de los fármacos , Caries Dental/microbiología , Genes Bacterianos/efectos de los fármacos , Genes Bacterianos/genética , Lectinas/efectos de los fármacos , Glicoproteínas de Membrana/efectos de los fármacos , Análisis por Matrices de Proteínas/métodos , ARN/aislamiento & purificación , Conejos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Streptococcus mutans/genética , Streptococcus mutans/patogenicidad , Virulencia/efectos de los fármacosRESUMEN
Exogenously added polyphenoloxidase (EC 1.14.18.1), an enzyme which oxidizes tyrosine residues and is commonly found in many dietary components, abolished the aggregation of Streptococcus sobrinus 6715 by high-molecular-weight dextran. The enzyme decreased glucan-binding lectin and/or glucosyltransferase I activities.
Asunto(s)
Proteínas Bacterianas , Catecol Oxidasa/farmacología , Glucosiltransferasas , Plantas/química , Streptococcus sobrinus/efectos de los fármacos , Adhesión Bacteriana/efectos de los fármacos , Catecol Oxidasa/antagonistas & inhibidores , Recuento de Colonia Microbiana , Dextranos/farmacología , Glucanos/metabolismo , Humanos , Lectinas/metabolismo , Lectinas de Plantas , Plantas/enzimología , Proteínas/antagonistas & inhibidores , Proteínas/metabolismo , Streptococcus sobrinus/fisiologíaRESUMEN
Glucan-binding lectin (GBL) activity of Streptococcus sobrinus was significantly reduced by fluoride in the growth medium. Approximately 1.5 mM fluoride was required for a 50% reduction in GBL activity. In addition to the GBL, several other glucan-binding proteins were reduced when the bacteria were grown in subinhibitory fluoride. Fluoride had no effect on glucosyltransferases (GTFs), enzymes capable of converting sucrose into alpha-1,6-glucans. All the proteins were detected by use of enhanced chemiluminescence (ECL of fluorescein-labeled dextran) and Western blotting of renatured SDS-PAGE gels. The effects of fluoride on the bacteria were abrogated when the manganous ion was included in the growth medium. It thus appears that one mechanism of action of fluoridated water is its effects on glucan-binding proteins. The fluoride may be reducing metabolism of the mangano aquo ion, essential for expression of the glucan-binding proteins.