IDENTIFICATION AND ANALYSIS OF PCB DECHLORINATING ANAEROBIC ENRICHMENTS BY AMPLIFICATION - ACCURACY OF COMMUNITY STRUCTURE-BASED ON RESTRICTION ANALYSIS AND PARTIAL SEQUENCING OF 16S RIBOSOMAL-RNA GENES

The composition of polychlorinated biphenyl (PCB) dechlorinating mixed communities was analysed by restriction fragment length polymorphism of PCR amplified rDNAs (ARDRA) and partial sequencing of 16S rRNA gene s amplified from PCB degrading enrichments. Restriction analysis confi rms that the 16S rRNA genes amplified from PCB dechlorinating communit ies vary depending on the PCB congener dechlorinated, Comparison of 16 S rRNA sequences to published ribosomal databases indicates that the t wo most abundant Operational Taxonomic Units (OTUs) appear to be speci es of the genus Clostridium. The amount that the amplification procedu re contributed to this result was determined by varying the amplificat ion procedure and by creating an artificial template mixture. Varying the amount of template by sixfold in the amplification did not affect the distribution of OTUs but the number of OTUs observed decreased wit h decreasing template concentration. Comparison of products amplified from mixtures of 16S rDNA clones indicates that the more abundant Clos tridium OTU did not amplify more efficiently than those of less abunda nt OTUs. Hybridization to a probe designed to detect the most abundant OTUs indicates that two other OTUs are closely related to this Clostr idium species.