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28-12-2011 | Article

Oral microbiota differs in healthy, gingival gums


Free abstract

MedWire News: Researchers have elucidated the diversity and population structure of the oral microbiota and identified a number of organisms that are potential biomarkers for gingivitis.

They say that their study, which used pyrosequencing of 16S rDNA amplicons, offers important insights into sampling and analysis strategies for unraveling gingivitis-associated microbial risk factors in human populations.

Jian Xu (Chinese Academy of Sciences, Qingdao, Shandong, China) and co-workers obtained samples of plaque and saliva from six individuals. All were healthy, nonsmoking adults aged between 21 and 30 years, and three had gingivitis.

The team used pyrosequencing to determine the sequences and relative abundance of the bacterial 16S rDNA PCR amplicons. "Sequence data were analyzed via a computational pipeline customized for human oral microbiome analyses," note Xu et al in the open-access journal BMC Oral Health.

Sequencing resulted in a dataset of 258,385 unique sequences, which were clustered into operational taxonomic units, giving between 464 and 737 different "species level" phylotypes per microbiome.

Further analysis showed that saliva microbiota was distinct from the plaque microbiota, and that plaque microbiota from people with gingivitis was distinct from that of people with healthy gums.

"Therefore, gingivitis- and healthy-gingival-microbiomes can be distinguished based on the distinct community structures of plaque microbiomes, but not the salivary microbiomes," write the researchers.

Finally, the team compared the bacterial phyla and genera samples against reference databases. All sequences were distributed in 11 bacterial phyla that include six predominant phyla commonly found in the mouth: Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, Fusobacteria, and TM7.

Interestingly, levels of Actinobacteria and Bacteroidetes were lower in people with gingivitis than those with healthy gums, whereas levels of the remaining phyla were raised in gingival samples.

Xu and co-authors conclude: "These results have important implications in the sampling and analysis strategies for surveying gingivitis-associated microbial risk factors. Our findings now enable further studies that examine the temporal development and epidemiology of microbial risk factors behind gingivitis."

By Joanna Lyford