- Volume 34, Issue 3, 1984

Deoxyribonucleic acid homologies were determined between five fast-growing soybean-nodulating strains from the People’s Republic of China and other rhizobia. Type strains Rhizobium trifolii ATCC 14480, Rhizobium meliloti ATCC 9930, Rhizobium phaseoli ATCC 14482, Rhizobium leguminosarum ATCC 10004, and Bradyrhizobium japonicum ATCC 10324 were used to represent recognized species. Bradyrhizobium sp. (Lupinus) strain ATCC 10319, the type strain of the former species Rhizobium lupini, and Bradyrhizobium sp. strain 3G4b5 were also included. The fast-growing soybean-nodulating strains had low levels of deoxyribonucleic acid homology with the type strains studied (5 to 43%). The fast-growing soybean-nodulating strains studied constitute at least two distinct deoxyribonucleic acid homology groups.

Deleya halophila sp. nov., which was isolated from hypersaline soils, is proposed. Each of 38 isolates, together with 8 reference strains, was examined in 97 phenotypic tests, and the data were analyzed by numerical taxonomy procedures. The 38 isolates formed a distinct group at a 76% similarity value, as determined by an analysis performed with the simple matching coefficient and unweighted average linkage clustering. Characteristically, the isolates were aerobic, gram-negative rods that were motile by one to eight peritrichous flagella. They grew optimally in the presence of 7.5% (wt/vol) marine salts. The distinguishing features of the new species are its salt requirement, biochemical features, and nutritional versatility. The guanine-plus-cytosine content of the deoxyribonucleic acid is 66.7 mol%. The type strain of this species is strain F5-7 (= CCM 3662).

Various species of bacteria belonging to taxonomically separate genera were studied by using electron microscopy and different cytochemical staining methods. Judging from our results and those reported previously in the literature, we concluded that the periodic acid-thiocarbohydrazide-silver proteinate reaction (Thiery method) separates the bacteria into four large groups according to the production of silver grains at the site of the cell wall or the cytoplasmic membrane or both. In the Corynebacterium-Mycobacterium-Nocardia group only the cytoplasmic membrane reacts; in Bacillus and Brucella only the cell wall reacts; in Lactobacillus and Microbacterium both the cell wall and the cytoplasmic membrane react; and in Escherichia and Clostridium neither the cell wall nor the cytoplasmic membrane reacts. Moreover, this staining method clearly separated Mycobacterium leprae from certain leprosy-derived coryneform bacteria.

Using phenotypic characterization, we found that 17 strains of asaccharolytic pigmented Bacteroides species isolated from soft-tissue infections in cats could be divided into five distinct groups. All of these strains were catalase positive, required vitamin K-hemin for growth, did not grow in bile, and did not exhibit α-glucosidase activity. The organisms in groups A and E (five strains) did not fluoresce under ultraviolet light at 365 nm and were indole positive. Group A organisms hemagglutinated sheep erythrocytes, but group E strains did not. The members of both of these groups produced large amounts of phenylacetic acid (group A average, 497 μg/ml; group E average, 404 μg/ml), and both groups showed trypsin-like activity (detected by using N-benzoyl-dl-arginine-2-napthylamide). The guanine-plus-cytosine contents of the deoxyribonucleic acids of group A strains ranged from 48 to 51 mol%; group E strain guanine-plus-cytosine contents ranged from 44 to 47 mol%. The members of groups B, C, and D (12 strains) all fluoresced and were indole positive. Group D strains hemagglutinated sheep erythrocytes, whereas groups B and C strains did not. Trypsin-like activity occurred in groups C and D but not in group B, and all strains produced phenylacetic acid (group B average, 11 μg/ml; group C average, 313 μg/ml; group D average, 999 μg/ml). The group B, C, and D, deoxyribonucleic acids had the following guanine-plus-cytosine contents: group B, 45 to 47 mol%; group C, 45 to 48 mol%; group D, 49 to 50 mol%. All groups of strains differed phenotypically and by isoelectric focusing of bacterial proteins from the asaccharolytic pigmented type strains Bacteroides gingivalis ATCC 33277 and Bacteroides asaccharolyticus ATCC 25260; they were different also from the saccharolytic pigmented type strains Bacteroides levii ATCC 29147, Bacteroides intermedius ATCC 25611, and Bacteroides macacae ATCC 33141.

A new species of Prosthecomicrobium, Prosthecomicrobium hirschii (type strain, ATCC 27832), is named in honor of Peter Hirsch. The range of cell morphology of this new species overlaps that of species in the genera Prosthecomicrobium and Ancalomicrobium. Populations of P. hirschii contain some cells with short appendages, like cells of members of the genus Prosthecomicrobium. However, cells that have long appendages characteristic of the genus Ancalomicrobium are also found in the same cultures. Motile cells have single polar to subpolar flagella. Gas vacuoles have not been detected. Either short- or long-appendaged cells can serve as mother cells in bud formation. Slide cultures indicate that a cell of a particular morphological type continues to divide to produce that same morphological type for several generations. The factor(s) that determines which cell type is produced is not presently understood. A variety of organic carbon sources, including formate, methanol, and ethanol, can be used for growth. The generic description is modified to include a greater variety of prosthecal types and the budding form of division, which is a property of all previously described species and the new species of Prosthecomicrobium emend.

Forty strains of Actinobacillus lignieresii, Actinobacillus equuli, Actinobacillus suis, Actinobacillus capsulatus, and Pasteurella ureae were 30 to 100% related as determined by deoxyribonucleic acid (DNA)-DNA hybridization (S1 nuclease method) and could be subdivided into five DNA hybridization groups. The DNA relatedness among A. suis, A. equuli, and P. ureae strains is indicative of some overlap among these three species. A comparison of DNA relatedness data with phenetic data showed that no single test can definitely separate A. suis from A. equuli. “Actinobacillus salpingitidis” the Actinobacillus sp. described by Ross et al. (Int. J. Syst. Bacteriol. 22:39-46, 1972), “Actinobacillus seminis,” Actinobacillus actinomy-cetemcomitans, Pasteurella multocida, Pasteurella haemolytica, Pasteurella aerogenes, Pasteurella gallinarum, Pasteurella pneumotropica, “Pasteurella betti,” “Pasteurella anatipestifer,” and Pasteurella testudinis were only 0 to 11% related to P. ureae, A. suis, A. equuli, A. capsulatus, and A. lignieresii.

Five strains of actinomyces isolated from the dental plaque of cattle were assigned presumptively to the genus Actinomyces on the basis of Gram staining, colonial and cellular morphology, fermentation reactions, and acid end products of metabolism. This assignment was confirmed by the molar composition of peptidoglycans. The isolates formed a homogeneous group on the basis of the sodium dodecyl sulfatepolyacrylamide electrophoresis patterns of their polypeptides, their cell wall carbohydrate constituents, and their deoxyribonucleic acid mean base compositions. They were also clearly related as determined by deoxyribonucleic acid-deoxyribonucleic acid homology, which distinguished them from strains of Actinomyces naeslundii, Actinomyces viscosus, and “Actinomyces denticolens.” A new taxon, Actinomyces howellii, is proposed for these strains, the type strain of which is strain NCTC 11636.

A total of 28 strains, representing 10 species of Legionella and including strains belonging to most of the known serogroups of each species, were examined for location, content, and composition of cellular nonhydroxy, monohydroxy , and dihydroxy fatty acids. The nonhydroxy fatty acid profiles were in agreement with previously published values. All species contained 5 to 15 mol% (depending on species) monohydroxy fatty acid, the profile of each species being readily distinguishable from the profiles of the other species. Only two species, Legionella pneumophila and Legionella micdadei, contained detectable levels of dihydroxy fatty acids, which comprised 1 to 5 mol% of the total fatty acids. The dihydroxy fatty acid profiles of these two species were significantly different. In all species, the nonhydroxy fatty acids were readily extractable by lipid solvents and were labile when subjected to mild alkaline methanolysis (lipid associated, ester linked), whereas the hydroxylated components were not extractable, were stable when subjected to alkaline methanolysis, and were labile when subjected to acid hydrolysis (bound, amide linked). The monohydroxy fatty acids were shown to be acids of the 3-hydroxy family. The dihydroxy fatty acids were shown to be members of the 2,3-dihydroxy family. The profiles of the hydroxylated fatty acids provide a powerful method for differentiating the Legionella species, particularly those species whose nonhydroxy fatty acid profiles are quite similar.

Strains of enterococci obtained from the American Type Culture Collection and the Centers for Disease Control were examined for deoxyribonucleic acid homology by using the S1 nuclease technique. The strains studied segregated into four homology groups. All five Streptococcus faecium strains were included in a single homology group (group III), and both Streptococcus faecalis strains were included in a separate homology group (group IV). Of eight “Streptococcus durans” strains, six fell into one homology group (group I), and two fell into a second homology group (group II). The four homology groups were easily distinguished phenotypically. All eight “S. durans” strains were inactive on mannitol, sorbitol, and arabinose. Group I strains clotted litmus milk but did not form acid from sucrose. Group II strains did not clot litmus milk but formed acid from sucrose. These results are consistent with a classification scheme in which “S. durans” is a separate species. We propose that the strains included in homology group I be designated Streptococcus durans sp. nov. and that strain ATCC 19432 be the type strain of this species. The two strains in homology group II may represent a new species, but the data supporting such a proposal are presently insufficient.

We propose the name Streptococcus macacae sp. nov. for gram-positive, catalase-negative streptococcal strains that were isolated from the dental plaque of monkeys (Macaca fascicularis). This organism is distinct from other oral streptococci in that it produces acid from mannitol and raffinose but not from inulin or dextrin. It is not able to grow in the presence of bacitracin and does not produce hydrogen peroxide or hydrolyze arginine, but esculin is hydrolyzed, and dextran is produced from sucrose. Streptococcus macacae sp. nov. possesses the serotype c antigen described by Bratthall, as do Streptococcus mutans and Streptococcus ferus; however, the protein profiles of whole-cell extracts subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and differences in deoxyribonucleic acid composition demonstrate that the new isolates are distinct from the two other species that possess the serotype c antigen and from other mutans streptococci. The guanine-plus-cytosine content of S. macacae is 35 to 36 mol%. The type strain is strain 25-1 (- NCTC 11558).

Biochemical, genomic, and serological data indicate that strains currently referred to as Listeria monocytogenes serovar 5 are sufficiently distinct from other species of the genus Listeria to merit separate species status. It is proposed that these strains be designated Listeria ivanovii sp. nov. The type strain of L. ivanovii is strain SLCC 2379 (= ATCC 19119).

I propose that the genus Ectothiorhodospira be placed in a new family, the Ectothiorhodospiraceae, as the only genus. The reasons for this proposal are discussed briefly, and a description of the new family and an emended description of the Chromatiaceae are given.

A rearrangement of the species of the “purple nonsulfur bacteria” (Rhodospirillaceae) is proposed. The species with vesicular intracytoplasmic membranes are removed from the genus Rhodopseudomonas and are placed in the new genera Rhodobacter and Rhodopila as Rhodobacter capsulatus (type species), Rhodobacter sphaeroides, Rhodobacter sulfidophilus, Rhodobacter adriaticus, and Rhodopila globiformis (type species). Rhodopseudomonas gelatinosa and Rhodospirillum tenue are united with Rhodocyclus purpureus (type species) in the genus Rhodocyclus as Rhodocyclus gelatinosus and Rhodocyclus tenuis. The decisions for this rearrangement were based mainly upon morphological and physiological properties; supporting arguments were based on structural similarities of macromolecular cell constituents.

Although Thioploca ingrica has not been isolated in pure culture and was omitted from the Approved Lists of Bacterial Names, the distinctive gross morphology of this species makes definitive identification possible through microscopic examination. The morphological description given here provides the type description (Rule 18a) and revives the name Thioploca ingrica sp. nov. ; this organism was originally named and recognizably described by Visloukh in 1911.

Species of the Acholeplasmataceae differ from species of the Mycoplasmataceae and Spiroplasmataceae in many respects, including lack of a nutritional requirement for sterol, ability of most species to synthesize saturated fatty acids and polyterpenes from acetate, and several other properties related to lipid metabolism and to the incorporation and location of lipids in the cell membrane. Acholeplasma species have also been found to differ from Mycoplasma species in possessing a nicotinamide adenine dinucleotide-dependent lactate dehydrogenase that is specifically activated by fructose 1,6-diphosphate and in containing superoxide dismutase, as well as glucose-6-phosphate and 6-phosphogluconate dehydrogenases. In addition, reduced nicotinamide adenine dinucleotide oxidase activity is located in the cell membrane of Acholeplasma species and is associated with the soluble cytoplasmic fraction of Mycoplasma and Spiroplasma species. Finally, significant differences exist between the nucleic acids of the Acholeplasmataceae and the Mycoplasmataceae. The genome molecular weight for Acholeplasma species is about 1.0 × 109, compared with about 5.0 × 108 for species of the Mycoplasmataceae. Moreover, a recent comparison of ribosomal ribonucleic acid oligonucleotide catalogs has demonstrated that Acholeplasma species are more closely related phylogenetically to two clostridial species than to the Mycoplasma and Spiroplasma species tested. Because the characteristics of species of the Acholeplasmataceae differ in major respects from those of other families of the Mollicutes, we propose elevation of the family Acholeplasmataceae to the rank of a new order, Acholeplasmatales. We provide a description of the proposed taxon, the second order of the class Mollicutes.