16S rDNA sequence diversity of a culture-accessible part of an anaerobic digestor bacterial community.

A bacterial culture-based inventory with 16S rDNA identification of the isolates was carried out on an anaerobic digestor microbial ecosystem to compare to the 16S rDNA sequences directly retrieved from the ecosystem by a molecular inventory previously made in our laboratory. Twenty OTUs (Operational Taxonomic Units) belonging to five of the major bacterial groups were identified from 338 isolated colonies. The sequences of 13 of the 20 OTUs were not closely related to any hitherto published sequences (less than 96% sequence identity). Six OTUs out of 20 were found to have sequences similar to sequences of the molecular inventory. Despite the biases expected to be associated with the molecular and culture-based methods, the distribution of the isolated OTUs into the different bacterial phyla was similar to that of the molecular OTUs.