ABSTRACT
Abstract There is growing evidence that C. albicans is associated with dental caries, but its role on caries development needs to be better clarified. Objective: To evaluate at the hard tissue level the effect of C. albicans on the cariogenic potential of S. mutans biofilms focusing on the mineral profile of induced carious lesions. This study also aimed to evaluate the effect of C. albicans on the acidogenic potential of S. mutans biofilms. Methodology: Dual-species (CA+SM) and single-species biofilms (CA or SM) were grown on the surface of enamel slabs in the presence of glucose/sucrose supplemented culture medium for 24, 48 and 72 hours. Demineralization was evaluated through percentage of surface microhardness change (%SMC) and transversal microradiography analysis (ILM and LD) and pH of the spent medium was recorded daily. Data were analyzed by two-way ANOVA followed by Bonferroni correction. Results: %SMC was statistically different among the biofilms at each time point being the highest for SM biofilms and the lowest for CA biofilms which also differed from CA+SM biofilms [SM (24 h: 47.0±7.3; 48 h: 66.3±8.3; 72 h: 75.4±3.9); CA (24 h: 7.3±3.3; 48 h: 7.1±6.4; 72 h: 6.6±3.6); CA+SM (24 h: 35.9±7.39.1; 48 h: 47.2±9.5; 72 h: 47.6±9.5)]. pH of spent medium was statistically lower for SM biofilms compared to the other biofilms at each time point and remained constant over time while pH values increased from 24 to 72 h for both CA and CA+SM biofilms [SM (24 h: 4.4±0.1; 48 h: 4.4±0.1; 72 h: 4.5±0.1); CA (24 h: 6.9±0.3; 48 h: 7.2±0.2; 72 h: 7.5±0.2); CA+MS (24 h: 4.7±0.2; 48 h: 5.1±0.1; 72 h: 6.1±0.6)]. IML and LD for SM biofilms increased over time while no difference was observed from 24 to 72 h for the other biofilms. Conclusions: The present data suggest that C. albicans has low enamel demineralization potential and the presence of C. albicans can reduce both the cariogenic and acidogenic potentials of S. mutans biofilms.
Subject(s)
Animals , Cattle , Streptococcus mutans/metabolism , Candida albicans/physiology , Tooth Demineralization/microbiology , Biofilms/growth & development , Dental Enamel/microbiology , Reference Values , Surface Properties , Time Factors , Acids/metabolism , Microradiography/methods , Colony Count, Microbial , Dental Enamel/chemistry , Hardness Tests , Hydrogen-Ion ConcentrationABSTRACT
ABSTRACT Lignocellulose-derived inhibitors have negative effects on the ethanol fermentation capacity of Saccharomyces cerevisiae. In this study, the effects of eight typical inhibitors, including weak acids, furans, and phenols, on glucose and xylose co-fermentation of the recombinant xylose-fermenting flocculating industrial S. cerevisiae strain NAPX37 were evaluated by batch fermentation. Inhibition on glucose fermentation, not that on xylose fermentation, correlated with delayed cell growth. The weak acids and the phenols showed additive effects. The effect of inhibitors on glucose fermentation was as follows (from strongest to weakest): vanillin > phenol > syringaldehyde > 5-HMF > furfural > levulinic acid > acetic acid > formic acid. The effect of inhibitors on xylose fermentation was as follows (from strongest to weakest): phenol > vanillin > syringaldehyde > furfural > 5-HMF > formic acid > levulinic acid > acetic acid. The NAPX37 strain showed substantial tolerance to typical inhibitors and showed good fermentation characteristics, when a medium with inhibitor cocktail or rape straw hydrolysate was used. This research provides important clues for inhibitors tolerance of recombinant industrial xylose-fermenting S. cerevisiae.
Subject(s)
Saccharomyces cerevisiae/drug effects , Xylose/metabolism , Glucose/metabolism , Phenols/metabolism , Phenols/pharmacology , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Acids/metabolism , Acids/pharmacology , Industrial Microbiology , Fermentation , Furans/metabolism , Furans/pharmacologyABSTRACT
Microbiologically induced deterioration (MID) causes corrosion of concrete by producing acids (including organic and inorganic acids) that degrade concrete components and thus compromise the integrity of sewer pipelines and other structures, creating significant problems worldwide. Understanding of the fundamental corrosion process and the causal agents will help us develop an appropriate strategy to minimize the costs in repairs. This review presents how microorganisms induce the deterioration of concrete, including the organisms involved and their colonization and succession on concrete, the microbial deterioration mechanism, the approaches of studying MID and safeguards against concrete biodeterioration. In addition, the uninvestigated research area of MID is also proposed.
Subject(s)
Corrosion , Construction Materials/microbiology , Environmental Microbiology , Acids/metabolismABSTRACT
O presente trabalho foi realizado objetivando-se comparar a eficiência de dois métodos analíticos, um por cromatografia líquida de alta eficiência (CLAE) e outro por cromatografia em fase gasosa com coluna capilar (CG), na determinação conjunta do ácido hipúrico (AH) e ácido metil-hipúrico (AMH) em urina de indivíduos expostos ocupacionalmente ao tolueno e xileno. Após a validação analítica foi observado que o método CLAE apresentou melhores precisão intra e interensaio, porcentagem de recuperação e sensibilidade. Amostras de urina de trabalhadores expostos aos dois solventes em fábrica de tintas-latex foram analisadas pelos dois métodos validados e os resultados avaliados estatisticamente...
Subject(s)
Acids/metabolism , Creatinine , Occupational Exposure/analysis , Toluene , Toxicology , Urea/analysis , Xylenes , Chromatography, Gas , Chromatography, High Pressure Liquid/methods , Specimen HandlingABSTRACT
A finalidade primordial da monitorização biológica é proteger a saúde dos trabalhadores, prevenindo a exposição excessiva às substâncias químicas. O ácido trans,trans-mucônico (ttAM), um produto de biotransformação do benzeno, tem sido preconizado como um bioindicador sensível da exposição ao benzeno e este trabalho foi desenvolvido com o propósito de validar método de detecção do ttAM urinário, visando à sua utilização na biomonitorização de trabalhadores expostos a esse solvente. A técnica escolhida foi a cromatografia líquida de alta eficiência (CLAE) com coluna de fase-reversa, Lichrosorb RP 18, e detector de ultravioleta...