Taxonomic Studies on Arthrobacter nicotianae and Related Taxa: Description of Arthrobacter uratoxydans sp. nov. and Arthrobacter sulfureus sp. nov. and Reclassification of Brevibacterium protophormiae as Arthrobacter protophormiae comb. nov.

Abstract

DNA homology studies were performed on various strains of Arthrobacter and related organisms with peptidoglycans (mureins) of the A3α and A4α variations. Homology values above 20% show strains with the A4α variation to form a coherent group, which is here designated as the "nicotianae" group of organisms. Members of this group show homology values of lower than 20% with strains of the "globiformis" group (Arthrobacter globiformis and relatives), having a A3α peptidoglycan variation. However, the phylogenetic analysis of one representative of the "nicotianae" group by 16S rRNA cataloguing and the comparison of the data with those of A. globiformis, A. oxydans and A. atrocyaneus reveals a close relationship between members of the "nicotianae" and "globiformis" groups. These data indicate that the genus Arthrobacter contains two nuclei whose members can be distinguished from each other by the peptidoglycan type and the menaquinone composition. Strains forming the "nicotianae" group fell into several subgroups which are separated by DNA homology values of less than 50%, indicating the presence of at least 5 genospecies. The genetic data, supported by results of biochemical and physiological studies, provide sufficient grounds to allot the strain Cory nebacterium liquefaciens ATCC 14929 to Arthrobacter nicotianae, for the reclassification of Brevibacterium protophormiae as Arthrobacter protophormiae comb. nov. and for the description of two new species, Arthrobacter sulfureus sp. nov. and Arthrobacter uratoxydans sp. nov.