Comparison of Deoxyribonucleic Acid Homologies of Six Strains of Ammonia-Oxidizing Bacteria

We assessed polynucleotide sequence homologies among representative strains from four genera of ammonia-oxidizing bacteria, including three morphological types of the genus Nitrosomonas, by deoxyribonucleic acid-deoxyribonucleic acid hybridization. Our results indicate that there is little homology among the four genera which we examined. Furthermore, the low degree of homology among the morphological types of Nitrosomonas suggests that each type should be considered a separate species.