Identification of the metabolically active members of a bacterial community in a polychlorinated biphenyl polluted moorland soil

The presumptive metabolically active members of a bacterial community in a moorland soil in Germany, highly polluted with polychlorinated biphenyls (P CBs), were identified by sequencing of cloned reverse transcription-polymer ase chain reaction (RT-PCR) amplification products of 16S rRNA generated fr om total RNA extracts, Analysis of the 16S rRNA clone library revealed a co nsiderable diversity of metabolically active bacteria in the soil, despite the acidic pH and high concentrations of PCBs, Cloned sequence types cluste red within the Proteobacteria (34% alpha-, 33% beta- and 7% gamma-subclasse s), the Holo-phaga-Acidobacterium phylum (14%), the Actinobacteria (6.5%) a nd the Planctomycetales (2%), Three cloned sequence types were not affiliat ed to any described phylogenetic group. An unusual feature of this soil was the abundance of sequence types within the beta-subclass of the Proteobact eria, most of which were similar to the 16S rRNA gene sequences of species from only two genera, Burkholderia and Variovorax. Three other numerous 16S rRNA sequence types were similar to the sequences of Sphingomonas species, members of the Rhodopila globiformis group and Acidobacterium capsulatum, Some of the sequence types retrieved were similar to the 16S rRNA sequences of bacterial isolates able to degrade a variety of organic pollutants, inc luding PCBs, As the PCB contamination is the major source of measurable car bon in this soil, some of the 16S rRNA sequence types detected and presumed to represent the metabolically active members of the community indicate th e organisms likely to be involved, directly or indirectly, in the utilizati on of the PCBs as carbon and energy sources.