Attached
Objectives: The aim was to investigate the relationship between groups of bacteria identified by cluster analysis
of the DGGE fingerprints and the amounts and diversity of yeast present.
Methods: Bacterial and yeast populations in saliva samples from 24 adults were analysed using denaturing
gradient gel electrophoresis (DGGE) of the bacteria present and by yeast culture.
Results: Eubacterial DGGE banding patterns showed considerable variation between individuals. Seventy one
different amplicon bands were detected, the band number per saliva sample ranged from 21 to 39
(mean ± SD = 29.3 ± 4.9). Cluster and principal component analysis of the bacterial DGGE patterns yielded
three major clusters containing 20 of the samples. Seventeen of the 24 (71 %) saliva samples were yeast positive
with concentrations up to 103
cfu/rnl, Candida albicans was the predominant species in saliva samples although
six other yeast species, including Candida dubliniensis, Candida tropicalis, Candida kruse~ Candida guilliermondii,
Candida rugosa and Saccharomyces cerevisiae, were identified. The presence, concentration, and species of yeast in
samples showed no clear relationship to the bacterial clusters.
Conclusion: Despite indications of in vitro bacteria- yeast interactions, there was a lack of association between the
presence, identity and diversity of yeasts and the bacterial DGGE fingerprint clusters in saliva. This suggests
significant ecological individual-specificity of these associations in highly complex in vivo oral biofilm systems
under normal oral conditions.
