- Volume 25, Issue 4, 1975

Some features of deoxyribonucleic acid (DNA) from 41 Zymomonas strains from Zaïrese palm wines, Mexican pulque, and English beer and cider were determined. DNA base composition varies within the narrow range of 47.5 to 49.5 mol% guanine plus cytosine. DNA:DNA hybridizations in stringent conditions show high nucleotide sequence similarities of over 76% DNA duplexing (% D), but mostly over 90% D. There is one slightly aberrant strain with less than 32% D. The molecular weight of the Zymomonas genome is 1.5 x 109. Z. mobilis and Z. anaerobia have almost identical genomes. Our data do not support species differentiation.

A total of 1,054 strains was allocated to species of the genera Mycobacterium, Nocardia, and Gordona (the rhodochrous group) on the basis of 88 characters, and hypothetical median organisms (HMOs) were derived for each species. Numerical analysis was carried out, treating these HMOs as operational taxonomic units. The dendrogram obtained showed that strains received as members of the rhodochrous group, including “Mycobacterium” rhodochrous, and strains named previously by the present author as Gordona, constituted a taxon comparable to the genus Nocardia. The analysis showed two separable groups at a 70% M value (matching coefficient) level. One consisted of slowly growing mycobacteria (Mycobacterium subgenus Mycobacterium Tsukamura) and the second consisted of rapidly growing mycobacteria (Mycobacterium subgenus Mycomycobacterium Tsukamura), the genus Gordona (including the rhodochrous group) and Nocardia. Diagrammatic representation of the taxonomic relationships by taxonomic distances showed the same result. Four taxa, which might be regarded as separate genera, separated at higher M values. These included the slowly growing mycobacteria, the rapidly growing mycobacteria, the genus Gordona (rhodochrous group), and the genus Nocardia, respectively. The slowly growing mycobacteria seem to be only distantly related to the other three, which bear a close relationship with each other.

Using Yersinia enterocolitica Becht 18 as a standard reference, we obtained deoxyribonucleic acid base sequence homologies ranging from 79 to 100% for 11 additional isolates of the species representing 9 serotypes. These organisms, many of which exhibited dissimilar biochemical reactions, therefore belong to one and the same species. However, the degree of relatedness between Y. enterocolitica and the established members of the genus (Yersinia pestis and Yesinia pseudotuberculosis) was low (18 to 24%), approaching that obtained for some of 10 selected isolates of 7 other genera of Enterobacteriaceae (2 to 16%). These findings suggest that the proposal to include Y. enterocolitica within the genus Yersinia requires further evaluation.

For the first time strains of Siderocapsa eusphaera Skuja, A and G, have been obtained in pure culture from lake water. The morphological variation of these strains exceeds the species distinctions of the previously described members of the genus Siderocapsa and those of the closely related and little studied other members of the family Siderocapsaceae, such as Siderobacter Naumann, Sideromonas Cholodny, Sideronema Berger, Ferribacterium Brusoff. Studies of the developmental cycle and physiology have shown that the newly isolated, Siderocapsa-like bacteria belong to the genus Arthrobacter of the family Corynebacteriaceae Cohn and Dimmick. The type species of this genus, Arthrobacter globiformis, and also the species A. citreus and A. simplex have been shown to be capable of oxidizing manganese and iron, thus forming morphological structures characteristic of Siderocapsaceae. It is proposed, therefore, that the family Siderocapsaceae be abolished as an independent taxonomic entity and that the naturally occurring bacteria so far described as species of Siderocapsa be considered growth forms of Arthrobacter species developing under specific conditions of habitat. Strains A and G of Arthrobacter (Siderocapsa) are regarded as belonging to a new species for which the name Arthrobacter siderocapsulatus is proposed. The strains have been deposited in the All-Union Collection of Microorganisms and have been assigned the numbers BKM-B N 1122 and BKM-B N 1123, respectively. Strain BKM-B N 1122 is designated as the type strain of A. siderocapsulatus.

The Gram reactions and cell wall topographies of six strains of Haemophilus piscium, including the type strain, and four strains assigned to Haemophilus ducreyi were studied to elucidate the taxonomic position of the two species. All strains were predominantly gram negative when stained by the Gram method but showed differences in staining between individual cells. The six strains of H. piscium and one strain of H. ducreyi exhibited a cell wall of the gram-negative type, whereas the remaining three strains of H. ducreyi exhibited a cell wall structure typical of gram-positive microorganisms. The study thus confirms the classification of H. piscium as a gram-negative bacterium but indicates that the name H. ducreyi has been used for different groups of bacteria. Only one of the strains of H. ducreyi investigated can legitimately be assigned to the genus Haemophilus, and more information is required to settle the taxonomic position of the remaining three strains.

A pink, obligately themophilic (60 C), gram-negative, nonmotile, nonsporeforming, rod-shaped bacterium with a deoxyribonucleic acid base ratio of 64 to 65 mol% guanine plus cytosine has been repeatedly isolated from slightly alkaline, man-made and natural thermal aquatic environments. This bacterium (K-2 isolate) does not appear to have been described previously and it has been deposited with the American Type Culture Collection as an unidentified bacterium with the accession no. 27599.

A new subspecies, Gluconobacter oxydans subsp. sphaericus, is described. This subspecies differs from the other subspecies of G. oxydans, the only species recognized in the genus Gluconobacter, both in its morphology and in its vitamin requirement for growth: The cells of the new subspecies are spherical at any age of culture and in all environments tested, and the organism requires nicotinic acid for growth; it differs from all other gluconobacters in that it does not require pantothenic acid. The type strain is IFO 12467.

The name Actinoplanes rectilineatus sp.nov. is proposed for the organism formerly referred to as Actinoplanes sp. 7-10. It forms a very short, macroscopically visible, orange-brown aerial mycelium. Conidia formation has not been observed. Globose, lophotrichous spores with an average of 30 flagella per spore are formed in longitudinal rows in cylindrical sporangia. Diffusible pigments are produced. Nitrates are not reduced. The type strain has been assigned the Waksman Institute of Microbiology IMRU number 3919.

A numerical classification using a total of 105 characters showed that Gordona strains together with rhodochrous strains formed a cluster, suggesting that these organisms belong to the same genus. Nocardia rubra strains were incorporated into this cluster. Nocardia rubra has accordingly been transferred to the genus Gordona. As Gordona rubra would be a junior homonym of the name of a species already assigned to that genus and subsequently shown to be identical with Gordona rubropertincta, Gordona lentifragmenta Tsukamura nom.nov. has been proposed for the strains originally known under the name Nocardia rubra.

A simple and rapid procedure for the isolation of bacterial deoxyribonucleic acid is described. The deoxyribonucleic acid preparations are pure enough to determine the base composition by ultraviolet spectroscopy.

Inconsistencies in the results of methyl red and Voges-Proskauer tests of Klebsiella pneumoniae have been published. These inconsistencies result from the unresolved taxonomic position of K. aerogenes.