Classification of some coryneform bacteria in a new genus Aureobacterium.

Chemical, biochemical and morphological data indicate a close relationship between the taxa "Microbacterium liquefaciens", Arthrobacter flavescens, Arthrobacter terregens, "Corynebacterium barkeri", Curtobacterium saperdae and Curtobacterium testaceum. It is proposed that the above taxa be reclassified in a new genus Aureobacterium, as Aureobacterium liquefaciens nom. rev., comb. nov.; Aureobacterium flavescens comb. nov.; Aureobacterium terregens comb. nov.; Aureobacterium barkeri nom. rev., comb. nov.; Aureobacterium saperdae comb. nov. and Aureobacterium testaceum comb. nov. respectively.

A numerical taxonomic study of the genus Kurthia with a revised description of Kurthia zopfii and a description of Kurthia gibsonii sp. nov.

One hundred and twelve strains including fresh isolates of Kurthia from a wide variety of habitats and named reference strains of the genera Arthrobacter, Bacillus, Brevibacterium, Cellulomonas, Corynebacterium, Curtobacterium, "Flavobacterium', Kurthia, Microbacterium, Nocardia and Rhodococcus were tested for 192 morphological, cultural, biochemical, and physiological characters. Various numerical analyses were performed on the data. All reference strains and most fresh isolates of Kurthia formed a distinct group considered to represent the genus. This group was divided into two clusters: one contained the type strain of K. zopfii and was considered to represent that species; the other was considered to represent a new species for which the name K. gibsonii is proposed. The two species are distinguished from each other by nine characters. A few presumptive Kurthia isolates were separated from the main Kurthia group; their taxonomic position was not resolved. Low levels of phenetic similarity were found between Kurthia and the coryneform and nocardioform bacteria, and with most Bacillus spp. studied, suggesting little relationship with these groups. However evidence was obtained that Kurthia bears a closer relationship to some aerobic Bacillus spp. than to the coryneform bacteria.

The Vitamin Requirements of Kurthia zopfii and Kurthia gibsonii.

The vitamin requirements of 17 K. gibsonii strains, 41 K. zopfii strains and 11 presumptive Kurthia isolates which could not be assigned to either species, were determined. When supplied with Casamino acids and/or Casitone the K. gibsonii strains required biotin + thiamine for growth whereas the K. zopfii strains required biotin + thiamine + pantothenic acid. The difference in their requirements provides support for the existence of the two species within the genus. Eight of the 11 presumptive Kurthia isolates had vitamin requirements different from both K. zopfii and K. gibsonii; their taxonomic position remained unresolved.

Lipid Composition of Arthrobacter simplex, Arthrobacter tumescens and Possibly Related Taxa.

The fatty acid, menaquinone and polar lipid composition of Arthrobacter simplex, A. tumescens, "Brevibacterium lipolyticum", Nocardioides albus and N. luteus were examined. The results of the present and earlier studies indicate A. simplex and A. tumescens should be removed from the genus Arthrobacter. On the basis of lipid composition A. simplex, "B. lipolyticum", N. albus and N. luteus are closely related to each other but are quite distinct from all other coryneforms and actinomycetes examined to date. Arthrobacter tumescens possess a very characteristic fatty acid and polar lipid composition and on that basis can be clearly distinguished from A. simplex and related species and possibly warrants a new taxon.