- Volume 24, Issue 4, 1974

By deoxyribonucleic acid-deoxyribonucleic acid molecular hybridization, evidence was obtained that the bacteria of the Oxytocum group represent a distinct deoxyribonucleic acid homology group and are not indole-forming and gelatin-liquefying variants of Klebsiella aerogenes and Klebsiella pneumoniae (sensu lato), respectively, and not a subgroup within Klebsiella, as had been suggested previously. The establishment of a new, but presently unnamed, genus of Enterobacteriaceae, with one species, is proposed, represented by strain 497-2 of R. Hugh (ATCC 13182). Furthermore, none of a series of bacterial strains classified as Enterobacter, Hafnia, or Erwinia species was found to be related to Klebsiella or to the Oxytocum strains. The deoxyribonucleic acid reassociation values do not allow species differentiation within the true, indole-negative klebsiellae.

Fifteen strains of an anaerobic bacterium having a subpolar tuft of flagella twisted together to function as one large structure were isolated from cecal contents of ten laboratory mice, three wild mice, and a wild rat. The strains were weakly gram positive and saccharolytic, and produced butyric acid from fermented carbohydrates. Spores could not be demonstrated in any strain. The isolates formed a group that did not fit any described species of anaerobic bacterium. The name Eubacterium plexicaudatum is proposed for this organism. The type strain VPI 7582 (=ATCC 27514) was obtained from a laboratory mouse.

The International Working Group on Mycobacterial Taxonomy has undertaken a series of cooperative studies to standardize and establish reproducibility of tests that are useful for classifying and identifying mycobacteria. To date 25 techniques have been examined, and 5 of these met our rigorous criteria for reproducibility and differential power. The properties determined by these tests are urease activity, pigment production, tolerance to 5% NaCl, hydrolysis of Tween 80, and galactosidase activity.

The principles of the Kauffmann-White-Schema, of the species definition, and of the modern, realistic classification, published by the author, are summarized.

One hundred and five strains of gram-negative, fermentative bacteria, representing members of the Enterobacteriaceae together with strains of Vibrio and Aeromonas, were subjected to numerical taxonomy and deoxyribonucleic acid (DNA)/DNA reassociation studies. The numerical taxonomy sorted the strains into major clusters corresponding to Edwardsiella tarda, Escherichia coli, Citrobacter freundii, the tribe Klebsielleae, and Vibrio alginolyticus. Smaller clusters could be identified as Serratia marcescens, Hafnia alvei, and Shigella species. Seven reference strains were used in the DNA/DNA reassociation studies.Klebsiella pneumoniae at 60 C shared reassociation values of 80 to 100% with other strains of Klebsiella, 37 to 64% with Enterobacter spp., and lower values with Hafnia, Citrobacter, Serratia, and Escherichia coli. Phenetically, K. pneumoniae and Enterobacter aerogenes shared high relatedness, although they are only 41 to 64% related in the reassociation studies.Hafnia, Salmonella typhimurium, and Edwardsiella tarda showed little relatedness to any of the other strains included in this study. Both reference strains of Escherichia coli shared genetic resemblances greater than 65% at 60 C with Shigella and at least 70% with other strains of Escherichia coli. Overall, the agreement between numerical taxonomy and the DNA/DNA reassociation studies was satisfactory, with correlation coefficients ranging from 0.5 to 0.9. The choice of reference strains may well affect the correlation between the two techniques, and it is suggested that hypothetical median organisms be determined from the phenetic groupings and that actual strains that approximate to the hypothetical median organisms be used as reference strains for DNA reassociation.

During a bacteriological examination of materials from slaughtered swine, we isolated from hemorrhagic and markedly edematous mandibular lymph nodes strains of hemolytic streptococci belonging to groups C, E, L, S, and U; also isolated were beta-hemolytic strains that were not classifiable within any of the known serological groups A to U. Hyperimmune sera prepared with these strains contain antibodies that are specific in the homologous system only and are distinct from antibodies against group A to U strains. The strains were investigated for their biochemical and physiological properties. On the basis of the characters determined and because of repeated isolations made in different localities, it is proposed that the strains are representatives of a new serological group of hemolytic streptococci, for which we propose the designation “V”.

A collection of 36 gram-negative bacterial strains, showing some resemblance to moraxellae and possibly belonging to Moraxella or related genera, was examined by a number of conventional tests in three laboratories by members of the ICSB Subcommittee on the Taxonomy of Moraxella and Allied Bacteria. Eight of the strains were oxidase negative and could be classified as belonging to Acinetobacter. Of the 28 oxidase-positive strains, two were yellow-pigmented cocci, but differed markedly from neisseriae. A group of 11 rod-shaped strains, also pigmented to a greater or lesser extent, appeared related to Flavobacterium. Four unpigmented, mesophilic strains differed sufficiently to be unlikely members of Moraxella. Nine unpigmented psychrophilic strains, including two strains of Thornley’s Phenon 3, showed similarities to moraxellae, although most of them oxidized aldose sugars like acinetobacters. Further taxonomic studies of the psychrophilic group will be of particular interest. The strains described by Bijsterveld 1970) and by Sutton et al. 1972) appeared to be nearly identical, but differed from moraxellae sufficiently to be unlikely members of Moraxella.

Strain EB 101 (ATCC 17802) is designated the type strain of Vibrio parahaemolyticus (Fujino et al.) Sakazaki, Iwanami, and Fukumi, and the morphological, physiological, biochemical, and serological characteristics of this strain are described. The characteristics of the type strain are compared with those of 200 other strains of this species.

Isolates of Xanthomonas translucens f.sp. oryzicola readily produced phenylalanine deaminase 1 day after inoculation and tyrosinase and glucosidase 4 days after inoculation, but isolates of Xanthomonas oryzae showed no such enzymatic activities by the methods employed. These differences easily distinguish bacterial blight of rice (caused by X. oryzae) from leaf streak of rice (caused by X. translucens f.sp. oryzicola).

A large spirillum was isolated from a freshwater pond in West Bengal. Its deoxyribonucleic acid base composition (51 mol% guanine + cytosine) and cell diameter (0.9 to 1.2.) were similar to those of Aquaspirillum serpens and A. putridiconchylium. Although its characteristics corresponded more closely to those of the latter species than of any other, the spirillum is unique in having an unusually high temperature for optimal growth (41 C), in forming water-soluble pigments from tyrosine and tryptophan, and in several other nutritional, biochemical, and serological characteristics. On the basis of these differences, the isolate was proposed as a new species,Aquaspirillum bengal. The type strain was deposited with the American Type Culture Collection under the number 27641.

Six Mycoplasma isolates, comprising a new species of Mycoplasma, were isolated from grivit monkeys recently imported from Ethiopia. These isolates metabolized both arginine and glucose but not urea. Growth occurred anaerobically and aerobically in media containing 20% horse serum or 1% serum fraction but not in media without serum. By metabolic-inhibition and indirect immunofluorescent techniques, these strains were shown to be serologically related to each other but unrelated to 9 other species from man and monkeys as well as to HRC/292 simian isolates and 26 species isolated from other animals. By immunodiffusion techniques, major sharing of antigenic determinants with the human Mycoplasma strains was not observed. Although the host-parasite relationship of these isolates has not been determined, at the time of isolation they were not associated with disease in the grivit monkey. On the basis of these findings, we propose that these new isolates be recognized as constituting a new species, for which we propose the name Mycoplasma moatsii. The type strain is MK 405 (=ATCC 27625).

A new genus of methanogenic bacteria is described. The colonies produced by these bacteria are yellow, circular, and convex with lobate margins; an optical pattern of regular, light and dark striations throughout the colonies is a most unique and distinguishing characteristic. These striations are two cell lengths apart. Cells are gram negative and occur in filaments up to 100 in length. Tufts of polar flagella and a striated cell surface are revealed in electron micrographs; cell ends are blunt, not rounded. The deoxyribonucleic acid base composition of the type species is 45 mol% guanine plus cytosine. Formate or hydrogen and carbon dioxide serves as a substrate for methane formation and growth; acetate, pyruvate, methanol, ethanol, and benzoate do not. The name Methanospirillum is proposed for this new genus of spiral-shaped methanogenic bacteria. The type species, Methanospirillum hungatii sp. nov., is named in honor of R. E. Hungate. The type strain of M. hungatii is JF1 (ATCC 27890).

More than 70 characters of 55 strains of Achromobacter xylosoxidans were compared with those of the type strain of A. xylosoxidans, ATCC 27061 (= KM 543). Repeated examination of these 55 strains confirmed the stability of the flagellar morphology and biochemical reaction pattern and performed that the species can be recognized by these characters. Two strains of Alcaligenes faecalis, two strains of Alcaligenes denitrificans, five strains of Alcaligenes sp., and five strains of each of King groups IIIa and IIIb were identified as strains of A. xylosoxidans. The base compositions of the deoxyribonucleic acids of 20 strains are given. The cellular fatty acid composition of extractable and bound lipids of five strains was determined. The minimal characters for the identification of strains of A. xylosoxidans are presented.

Clostridium celatum sp.nov. was isolated from a number of fecal specimens at concentrations of 103 to 106 per gram (wet weight). The isolates are nonmotile, saccharolytic, nontoxic, nonhemolytic, and non-proteolytic. They reduce sulfite and nitrite and produce urease but no lecithinase or lipase; the major organic acids produced in peptone-glucose cultures are acetic and formic. American Type Culture Collection no. 27791, GD-1, is designated the type strain

A new species of Corynebacterium isolated from field corn is described. The isolates form a homogeneous group that is recognized as a new species,Corynebacterium nebraskense. The organism is characterized by orange-pig-mented colonies, inability to grow on 0.005% triphenyltetrazolium chloride agar, specific bacteriophage sensitivity, and a guanine plus cytosine content of 73.5 mol%. These and other characters differentiate this organism from other described phytopathogenic corynebacteria. The type strain of C. nebraskense is Fur-1 (= ATCC 27822 = NCPPB 2578).

Mycobacterium phlei ATCC 356 has been shown to be a strain of Mycobacterium smegmatis.

The descriptions of the genus Alcaligenes Castellani and Chalmers and Alcaligenes faecalis Castellani and Chalmers have been emended. It is requested that the Judicial Commission issue an Opinion rejecting the name Achromobacter Bergey et al. as a nomen dubium. It is proposed, on the basis of a comparison of type and reference strains, that Alcaligenes denitrificans Leifson and Hugh, Achromobacter arsenoxydans-tres Turner, and Alcaligenes odorans (Málek and Kazdoá Kžišková) Málek et al. be considered as subjective synonyms of A. faecalis. The proposed taxonomic status of all known previously described species of the genera Alcaligenes and Achromobacter is indicated in appendixes.