Polyphasic classification of Proteobacteria isolated from biofilters

70 Gram-negative, nonfermenting bacterial isolates from biofilters for off-gas treatment of animal-rendering plane emissions were analyzed for respiratory quinones, polyamine patterns, fatty acid profiles, physiological reaction profiles, and by reverse transcriptase partial sequencing of 16S rRNA. Based on these data, the isolates were grouped into six clusters, which were shown to belong to the alpha- and beta-subclass of the Proteobacteria. Inclusion of fifteen reference strains allowed the assignment of one cluster to the species Brevundimonas diminuta and the assignment of a second cluster to the species Alcaligenes faecalis. The 49 strains of the Brevundimonas diminuta cluster and the clusters F, H, and I were shown to belong to the alpha-subclass of the Proteobacteria. Paracoccus denitrificans evolved as the next neighbour of cluster F. The remaining 21 bacteria containing the beta-subclass specific polyamine 2-hydroxyputrescine grouped either into the Alcaligenes faecalis cluster or formed a distinct group (cluster J) representing a new taxon within the Alcaligenaceae.