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Stimulated-saliva, swabbing-plaque and brushing-plaque samples were successivelycollectedfrom five volunteers four times over a seven-day period and the number of total streptococci (TS) and mutans streptococci (MS) in each sample were determined using selective media. The percentages of MS in TS (MS%) of the brushing-plaque and the stimulated saliva, but not the swabbingplaque, were kept almost constant through a sampling period, and the ratio of mean MS% in both samples significantlyvaried among subjects.These findings suggestthat plaquesamplerecoveredby brushingtreatmentfor 1min is superior to stimulated whole saliva as a sampling material for assessment of individual caries risk.

Three Gram-positive, catalase-negative, coccus-shaped organisms were isolated from the oral cavities of bears. The isolates were tentatively identified as a streptococcal species based on the results of biochemical tests. Comparative 16S rRNA gene sequencing studies confirmed that the organisms were members of the genus Streptococcus, but they did not correspond to any recognized species of the genus. The nearest phylogenetic relative of the new isolates was Streptococcus ratti ATCC 19645 T (98.6 %), however, DNA-DNA hybridization analysis showed that the isolates displayed less than 15 % DNA-DNA relatedness with the type strain of S. ratti. Colonies of the novel strains grown on mitis salivarius agar showed an extracellular polysaccharide-producing colony morphology. Based on phenotypic and phylogenetic evidence, it is proposed that the novel isolates are classified in the genus Streptococcus as Streptococcus ursoris sp. nov. The type strain of S. ursoris is NUM 1615 T (5JCM 16316 T 5DSM 22768 T ).