Community analysis of a denitrifying reactor treating landfill leachate.

The bacterial community of a denitrifying reactor from a system for landfill leachate decontamination was studied applying cultivation methods, denitrifying activity measurements and characterisation of community 16S rDNA. The sludge presented a high denitrifying activity but a relatively low number of denitrifying bacteria as determined by most probable number. Over 50% of the sequences retrieved in the molecular analysis were related to genera with the capacity to denitrify in the alpha- and beta-subdivisions of the Proteobacteria. Fifteen percent of the DNAs were related to not yet cultured organisms belonging to the green non-sulphur phylum. High similarity values between sequences from isolates and clones were observed.