Identification of archaeal rDNA from subgingival dental plaque by PCR amplification and sequence analysis

A PCR assay for the amplification of small subunit ribosomal DNA (SSU rDNA) of Euryarchaea was developed and used to detect archaeal rDNA in 37 (77%) out of 48 pooled subgingival plaque samples from 48 patients suffering from periodontal disease. One major group of cloned periodontal sequences was i dentical to Methanobrevibacter oralis and a second minor group to Methanobr evibacter smithii. These two groups and a third novel group were found to b e more than 98% similar to each other over an 0.65-kb segment of the 16S rR NA gene sequenced, M. oralis was found to be the predominant archaeon in th e subgingival dental plaque. Phylogenetic analysis of partial SSU rDNA sequ ences revealed evidence for a distinct cluster for human and animal Methano brevibacter sp. within the Methanobacteriaceae family. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. A ll rights reserved.