[Not Available].

Area of Science:

• Microbiology
• Molecular Biology
• Genomics

Background:

• Human saliva separates into cellular and liquid phases via centrifugation.
• The cellular phase is known to harbor oral bacteria, but the liquid phase's microbial content is poorly understood.

Purpose of the Study:

• To investigate the presence and correlation of bacterial nucleic acids in the cell-free liquid phase of human saliva.
• To determine if the liquid phase reflects the oral microbiota composition found in the cellular phase.

Main Methods:

• Analysis of bacterial 16S ribosomal DNA (rDNA) and 16S ribosomal RNA (rRNA) in saliva liquid phase using universal bacterial primers.
• Polymerase chain reaction (PCR) amplification and sequencing of 16S rDNA from the liquid phase.
• Denaturing gradient gel electrophoresis (DGGE) to compare microbial profiles between liquid and cellular phases.

Main Results:

• Significant amounts of bacterial 16S rRNA and rDNA were detected in the cell-free saliva liquid phase.
• Sequencing identified 15 operational taxonomic units (OTUs) from the liquid phase amplicons.
• DGGE analysis revealed a strong positive correlation (Pearson Correlation=0.822, P<0.001) between microbial profiles of the liquid and cellular phases.

Conclusions:

• The liquid phase of human saliva contains abundant bacterial nucleic acids.
• These nucleic acids in the liquid phase correlate with the bacteria present in the cellular phase of saliva.
• The cell-free saliva supernatant can serve as a source of information about the oral microbiota.