Isolation and Characterization of a New Denitrifying Spirillum Capable of Anaerobic Degradation of Phenol

Two kinds of phenol-degrading denitrifying bacteria, Azoarcus sp. strain CC-11 and spiral bacterial strain CC-26, were isolated from the same enrichment culture after 1 and 3 years of incubation, respectively. Both strains required ferrous ions for growth, but strain CC-26 grew better than strain CC-11 grew under iron-limited conditions, which may have resulted in the observed change in the phenol-degrading bacteria during the enrichment process. Strain CC-26 grew on phenol, benzoate, and other aromatic compounds under denitrifying conditions. Phylogenetic analysis of 16S ribosomal DNA sequences revealed that this strain is most closely related to a Magnetospirillum sp., a member of the α subclass of the class Proteobacteria, and is the first strain of a denitrifying aromatic compound-degrading bacterium belonging to this group. Unlike previously described Magnetospirillum strains, however, this strain did not exhibit magnetotaxis. It grew on phenol only under denitrifying conditions. Other substrates, such as acetate, supported aerobic growth, and the strain exhibited microaerophilic features.