RESUMO
We aimed to determine the bacterial diversity of different oral micro-niches and to assess whether saliva and plaque samples are representative of oral microbial composition. We took minute samples from each surface of the individual teeth and gingival crevices of two healthy volunteers (112 samples per donor), as well as samples from the tongue dorsum and non-stimulated and stimulated saliva. DNA was extracted from 67 selected samples of each donor, and the 16S rRNA gene was amplified by PCR and pyrosequenced to obtain, on average, over 2,700 reads per sample, which were taxonomically assigned to obtain a geographic map of bacterial diversity at each tooth and sulcus location. Analysis of the data shows considerable differences in bacterial composition between teeth at different intra-oral locations and between surfaces of the same tooth. The most pronounced differences were observed in incisors and canines, where genera like Streptococcus were found at 40% to 70% on the vestibular surfaces but were almost absent on the lingual sides. Saliva samples, especially non-stimulated saliva, were not representative of supra-and subgingival plaque in the two individuals tested. We suggest that more precise sampling is required for the proper determination of oral microbial composition and to relate that diversity to epidemiological, clinical, and etiological parameters.
Assuntos
Bactérias/classificação , Boca/microbiologia , Actinobacillus/classificação , Actinomycetaceae/classificação , Adulto , Dente Pré-Molar/microbiologia , Capnocytophaga/classificação , Dente Canino/microbiologia , DNA Bacteriano/análise , Placa Dentária/microbiologia , Fusobacterium/classificação , Gengiva/microbiologia , Haemophilus/classificação , Humanos , Incisivo/microbiologia , Masculino , Dente Molar/microbiologia , Mucosa Bucal/microbiologia , Palato/microbiologia , Reação em Cadeia da Polimerase , Prevotella/classificação , RNA Bacteriano/análise , RNA Ribossômico 16S/análise , Saliva/microbiologia , Streptococcus/classificação , Língua/microbiologia , Veillonella/classificação , Adulto JovemRESUMO
A method has been developed for the determination of chromium in presence of V(V), Mo(VI), and Fe(III). The effects of interferences were evaluated by using the apparent content curves method, and their separation was performed by solid-phase extraction with an anionic exchanger. The sample-treatment conditions and the influence of the sample conductivity were studied. Tolerance limits were established, and the proposed procedure was used to determine chromium in certified samples and for speciation of chromium in waste water. Our results were always in agreement with the theoretical content.