Identification of xenobiotic-degrading isolates from the beta subclass of the Proteobacteria by a polyphasic approach including 16S rRNA partial sequencing.

Nineteen gram-negative, aerobic, biodegradative isolates were identified by using a polyphasic taxonomic approach. The presence of the specific polyamine 2-hydroxyputrescine and the presence of a ubiquinone with eight isoprenoid units in the side chain (ubiquinone Q-8) allowed allocation of these organisms to the beta subclass of the Proteobacteria. On the basis of the results of additional characterization experiments (i.e., API 20NE tests, determinations of soluble protein patterns, and DNA-DNA hybridization experiments), we classified six isolates as either Comamonas testosteroni, Comamonas acidovorans, or Alcaligenes xylosoxidans subsp. denitrificans. By using the same criteria we allocated two additional isolates to the genus Alcaligenes. A comparison of a 16S rRNA fragment (positions 1220 to 1377; Escherichia coli nomenclature) indicated that the remaining isolates should be allocated as follows: one is a member of C. testosteroni and one is a member of Acidovorax facilis, as confirmed by the results of additional DNA-DNA hybridizations; two others probably belong to the family Alcaligenaceae; six are related to "Alcaligenes eutrophus"; and one, strain NRRL 12228, occupies an isolated position.