Dechlorosoma suillum Achenbach et al. 2001 is a later subjective synonym of Azospira oryzae Reinhold-Hurek and Hurek 2000.

In order to clarify the taxonomic position of Dechlorosoma suillum, which shares 99.9% 16S rDNA sequence identity (1433 of 1435 bp) with Azospira oryzae, we compared the two species in a polyphasic taxonomic approach. Results of 122 physiological and biochemical tests for D. suillum DSM 13638T and Azospira oryzae 6a3T were identical, except for the lack of growth of Azospira oryzae 6a3T with perchlorate as the terminal electron acceptor. Presence of a nifH gene and nitrogenase activity, a key feature of Azospira, were also detected in D. suillum by Southern hybridization and by the acetylene reduction assay, respectively. Whole-cell SDS-PAGE profiles of SDS-soluble proteins of strains DSM 13638T and 6a3T were almost identical. DNA-DNA hybridization studies showed more than 90% binding between D. suillum and two strains of Azospira oryzae. These data provide evidence that the two bacteria belong to the same species and that D. suillum is a later subjective synonym of Azospira oryzae.