Taxonomy of the genus Acinetobacter with the recognition of Acinetobacter baumannii sp. nov., Acinetobacter haemolyticus sp. nov., Acinetobacter johnsonii sp. nov., and Acinetobacter junii sp. nov. and emended descriptions of Acinetobacter calcoaceticus and Acinetobacter lwoffii

Using deoxyribonucleic acid hybridization (S1 nuclease method), we identified 12 hybridization groups (genospecies) containing 74 strains among 85 Acinetobacter strains studied. A total of 28 characters which allowed identification of the genospecies were applied to 266 strains. Of the 12 genospecies, 11 could be unambiguously identified. Genospecies 1 (Acinetobacter calcoaceticus sensu stricto) contained eight glucose-oxidizing strains which were unable to grow at 44°C and were isolated from soil, including the type strain of A. calcoaceticus. Genospecies 2, which contained 121 strains (mostly glucose oxidizers that were able to grow at 44°C), was named Acinetobacter baumannii sp. nov. (type strain, strain ATCC 19606). Genospecies 3 contained 15 strains that were able to oxidize glucose and to grow at 41°C but not at 44°C. Genospecies 4, which contained 23 hemolytic and proteolytic strains that were able to utilize DL-4-aminobutyrate but not DL-lactate, was named Acinetobacter haemolyticus sp. nov. (type strain, strain ATCC 17906). Genospecies 5, which contained 17 strains that were unable to oxidize glucose and able to utilize DL-lactate and L-histidine but not glutarate or azelate, was named Acinetobacter junii sp. nov. (type strain, strain ATCC 17908). Genospecies 6 contained only three hemolytic, proteolytic strains that were unable to utilize DL-lactate, malonate, or DL-4-aminobutyrate. Genospecies 7, which contained 23 strains that were unable to grow at 37°C and to oxidize glucose and utilized only a few carbon sources was named Acinetobacter johnsonii sp. nov. (type strain, strain ATCC 17909). A total of 34 strains had the characteristics of genospecies 8/9 (mostly glucose negative; utilized azelate but not Simmons citrate, glutarate, L-histidine, L-aspartate, L-leucine, β-alanine, or 2,3-butanediol). Genospecies 8 was Acinetobacter lwoffii sensu stricto since it contained the type strain of this species. Genospecies 9 could not be differentiated from genospecies 8. Genospecies 10 (four strains), 11 (four strains), and 12 (three strains) were differentiated by their nutritional patterns.