- Volume 28, Issue 4, 1978

This study is a measurement of the moles percent guanine plus cytosine of 34 strains of bacteria belonging or related to the genus Enterobacter. All of the strains included in the sampling have been previously studied by numerical taxonomy, which has shown four new classes: H1, H2, H3, and d. The average guanine-plus-cytosine contents for the defined species and of the new classes are: Enterobacter cloacae (10 strains), 54.5 mol% (standard deviation, 1.32); Hafnia alvei (5 strains), 48.1 mol% (standard deviation, 1.0); Enterobacter agglomerans (syn. Erwinia herbicola) (1 strain), 52.4 mol% (standard deviation, 0.41); Serratia liquefaciens (1 strain), 50.9 mol% (standard deviation, 1.22); Enterobacter aerogenes (1 strain), 53.5 mol% (standard deviation, 0.29); class H1 (5 strains), 52.2 mol% (standard deviation, 1.3); class H2 (5 strains), 53.4 mol% (standard deviation, 1.9); class H3 (5 strains), 54.2 mol% (standard deviation, 0.1); class d (1 strain), 52.6 mol% (standard deviation, 1.45). The importance of the guanine-plus-cytosine contents for discriminating defined species and new classes is discussed.

Seven new isolates of Serratia plymuthica (including two from a human source) and 24 isolates resembling unclustered Serratia strain 38 (Grimont et al., J. Gen. Microbiol 98:39-66, 1977) are described. Deoxyribonucleic acid relatedness studies, obtained with labeled reference deoxyribonucleic acid from S. plymuthica 392 confirm that S. plymuthica is a discrete species. Mean percent relatedness of S. plymuthica isolates to strain 392 was 88 ± 13.6 (standard deviation), whereas the mean percent relatedness of S. liquefaciens isolates (the closest species) to strain 392 was 52 ± 12.4. Strain 38 and twenty-four “38-like“ isolates constitute a new deoxyribonucleic acid hybridization group that is 28 to 43% related to Serratia species and to the “Citrobacter-like” group of Leclerc and Buttiaux, and 15 to 22% related to other known species of Enterobacteriaceae. This 38-like group constitutes a new species that is named Serratia odorifera sp. nov. (type strain, ICPB 3995). Two biotypes (1 and 2) are described. Strains of this species will grow on caprylate-thallous agar (selective for Serratia spp.), and they have a characteristic odor. Most strains of S. odorifera were recovered from clinical specimens.

A numerical taxonomy analysis of Mycobacterium africanum strains from Rwanda (6 strains), Burundi (5 strains), Yaoundá (23 strains), Dakar (17 strains), and Mauretania (9 strains) indicated that these bacteria did not cluster separate from the M. tuberculosis or the M. bovis clusters, nor did they eliminate the phenetic discontinuity between the latter. However, the African strains introduced considerable heterogeneity in the usually homogeneous M. tuberculosis and M. bovis clusters. Judging from the data, it did not seem justifiable to create a new species M. africanum. Preliminary genetic analysis did not support the view expressed earlier that these bacteria mutated at high frequencies, and further genetic analysis of these bacteria seemed necessary.

Seventy-seven recently isolated bovine ureaplasma (T-mycoplasma) strains were compared by the growth inhibition test with previously reported strains. The complex serological nature of the group was confirmed. Only five of the fresh isolates did not react with antisera to the eight representative bovine strains proposed previously. The suggestion that the serological diversity of the group might be represented by a small number of strains has thus been confirmed. Eleven strains are proposed as representatives of this serological diversity. No common antigens were shown between Ureaplasma urealyticum, the ureaplasmas of human origin, and the bovine isolates.

Bacteroides microfusus sp. nov. is described on the basis of 16 strains isolated from a number of fecal or cecal specimens from calves, chickens, and Japanese quails. The isolates are obligately anaerobic, gram-negative, nonsporeforming, nonmotile, relatively small rods with pointed ends; the cells occur singly, in pairs, and sometimes in short chains. B. microfusus differs from other species in the genus Bacteroides principally in morphology; the small spindle-shaped cells, particularly on agar media, are rather distinctive. The guanine-plus-cytosine contents of the deoxyribonucleic acids of the new strains range from 59 to 61 mol%, the highest value so far detected in the genus Bacteroides. The new strains are similar to those of B. putredinis, B. furcosus, B. amylophilus, and B. succinogenes in fermenting a relatively small number of carbohydrates; however, B. microfusus can clearly be differentiated from these organisms by numerous biochemical properties and/or fermentation products. The type strain of B. microfusus is Q-1 (= ATCC 29728 = NCTC 11190).

Although the name Staphylococcus hyicus has appeared in the literature, it has never been validly published. Supportive evidence is given for the transfer of Micrococcus hyicus Sompolinsky to the genus Staphylococcus, and the name Staphylococcus hyicus (Sompolinsky) comb. nov. is proposed. A description of this organism is given on the basis of a taxonomic analysis of 168 strains of this species isolated from swine with infectious epidermitis, from the skin and nares of healthy pigs and poultry, and from cows with mastitis. One hundred thirty-two strains which produced unpigmented colonies and a heat-stable nuclease were placed in the type subspecies S. hyicus subsp. hyicus subsp. nov. Thirty-six pigmented strains were placed in the subspecies S. hyicus subsp. chromogenes subsp. nov. Strain NCTC 10350 (= CCM 2368 = ATCC 11249 = D. Sompolinsky no. 1) is here designated the type strain of S. hyicus and of S. hyicus subsp. hyicus, and strain NCTC 10530 (= A. C. Baird Parker CBCC 1462) is designated the type strain of S. hyicus subsp. chromogenes. A scheme for the differentiation of S. hyicus from certain other Staphylococcus species is included.

Bacteroides amylophilus ATCC 29744 and B. succinogenes ATCC 19169 are described and here designated the neotype strains of these two species.

Eleven glucose-fermenting Mycoplasma strains isolated from the cervix region of mares exhibited serological properties which distinguished them from strains of the presently known Mycoplasma species. From the results obtained by growth inhibition, metabolic inhibition, indirect-immunofluorescence, and double-im-munodiffusion tests, it can be concluded that these strains belong to a new species, for which the name Mycoplasma equigenitalium is proposed. The type strain of M. equigenitalium is T37 (= ATCC 29869 = NCTC 10176).

In 1919, Paine and Stansfield attributed a leaf-spot disease of the tropical plant Protea cynaroides to Pseudomonas proteamaculans. This organism, placed at various times in the genera Xanthomonas, Erwinia, and Enterobacter and now known as Erwinia proteamaculans (Paine and Stansfield 1919) Dye 1966, is listed in the first (1976) draft of the Approved List of Bacterial Names. We demonstrate here—on the basis of biochemical properties, polynucleotide sequence relatedness, and pathobiological capacity—the identity of (i) the only strain (ATCC 19323 = Dye ZL1 = ICPB XP176 = NCPPB 245; here designated as the type strain of P. proteamaculans) of E. proteamaculans still extant from the Paine and Stansfield study with (ii) Serratia liquefaciens biotype C1c. Based on the results of our study, we recommend the transfer of E. proteamaculans to the genus Serratia. Serratia proteamaculans (Paine and Stansfield 1919) comb. nov. is to be regarded as a senior subjective synonym of S. liquefaciens (Grimes and Hennerty 1931) Bascomb et al. 1971.

The deoxyribonucleic acid base sequence similarities among 14 strains of Streptococcus mitior were assessed by hybridization. Some strains produce glucan. Deoxyribonucleic acid was purified by both a conventional method and by centrifugation in CsCl. Hybridizations were done in solution with S1 nuclease and on membrane filters. The results showed two groups of moderately homologous strains. The glucan-producing strains represented a group which included some glucan-negative strains. Hybridization by the S1 method was less than with the filter method, indicating some sequence divergence within the two groups. There was a slight difference in guanine-plus-cytosine contents of the two groups.

Strains of several genetically important Streptomyces species and four strains of Nocardia mediterranei were screened for nutritional properties by using 150 different organic compounds. The methodology for an extensive nutritional analysis of actinomycetes is described, and the results are discussed on the basis of their taxonomic and ecological implications.

Studies on 15 dextrin-fermenting, L-(+)-lactic acid-producing pediococci, including two strains originally described in 1964 by Coster and White under the name Pediococcus cerevisiae var. (= subsp.) dextrinicus, and 13 new isolates from beer, beer bottles, silage, and spent grains showed that these strains represent a distinct, well defined species. This species can be distinguished from all other pediococci by the following: Its carbohydrate fermentation, especially starch hydrolysis; the electrophoretic mobility of its lactate dehydrogenase; and the production of a fructose-1,6-diphosphate-activated L-lactate dehydrogenase. In this paper, P. cerevisiae subsp. dextrinicus is elevated to the rank of species. The name of this species is Pediococcus dextrinicus (Coster and White) comb. nov. strain DSM 20335 is designated as the type strain of P. dextrinicus. A culture of this strain has been deposited in the Deutsche Sammlung von Mikroorganismen, Germany.

The deoxyribonucleic acid (DNA) relationships among strains of the thermophilic species Clostridium thermohydrosulfuricum, C. thermosaccharolyticum, and C. tartarivorum, other saccharolytic, proteolytic, and acetate-producing clostridia, and some sulfate-reducing bacteria were studied by DNA-DNA hybridization experiments. Strains of the species C. thermohydrosulfuricum were found to constitute a genotypically homogeneous group clearly unrelated to the strains of the species C. thermosaccharolyticum and other competitor strains used. Strains of the species C. tartarivorum showed a high level of homology with the reference strain C. thermosaccharolyticum ATCC 7956. The guanine-plus-cytosine contents of the acetate-forming clostridia C. formicoaceticum and C. thermoaceticum were 34.0 and 54.0 mol%, respectively.

An examination of all known strains labeled Pseudomonas melophthora Allen and Riker 1932 and of the herein-designated type strain of P. pomi Cole 1959 (strain PDDCC 3878 [= NCPPB 463]) showed that they were similar to one another but atypical of members of the genus Pseudomonas Migula 1894. Because these organisms were found to be either motile (peritrichous cells) or nonmotile, able to grow at low pH values, and to oxidize ethanol and lactate to carbonate, it is suggested that they belong to Acetobacter Biejerinck 1898. P. pomi is regarded here as being a subjective junior synonym of A. pasteurianus (Hansen 1897) Beijerinck 1898, and P. melophthora is regarded here as being a nomen dubium. Isolates of P. pomi and similar organisms capable of inducing necrosis in apple fruit should be classified in A. pasteurianus until the relationships of pathogenic strains within the species are better understood.

Eighteen arginine-positive and 32 glucose-fermenting Mycoplasma strains were isolated from tracheas and oropharynxes of pigeons. Biochemical and serological studies revealed that these isolates were distinguished from all of the currently accepted Mycoplasma species and serogroups. The 18 arginine-positive pigeon strains appear to constitute a new species, for which the name Mycoplasma columbinum is proposed. The type strain of M. columbinum is MMP1 (= ATCC 29257 = NCTC 00000). The 32 glucose-fermenting pigeon strains constitute another new species, for which the name Mycoplasma columborale is proposed. The type strain of M. columborale is MMP4 (= ATCC 29258 = NCTC 00000).

The fused rocket immunoelectrophoresis procedure is a sensitive procedure for detecting precipitating antigens in extracts of mycobacteria. A number of preparations can be run simultaneously and in parallel with the production of lines of identity. The increased sensitivity and facility of identification make this procedure a very promising one in the study of taxonomic relationships.

Bacterium J217 was isolated from approximately 100 cm below the sediment water interface of the Irish Sea. It is a small, gram-negative, nonmotile rod with a guanine-plus-cytosine content of 67.5 mol%. J217 is an obligate aerobe that is catalase positive and cytochrome oxidase positive. It is nonfermentative, does not hydrolyze complex molecules, and is resistant to seven antibiotics but is susceptible to polymyxin B. Branched-chain amino acids are required for growth; flavine adenine dinucleotide or riboflavine 5’-phosphate and pyridoxal phosphate are necessary cofactors. The temperature, pH, and salinity are narrowly defined with optima at 23°C, pH 7.3, and 36% salinity, respectively. Sodium ions are required for growth and multiplication. Spectral analyses of the yellow, carotenoid pigment produced by J217 are similar to those associated with McMeekin type 2 bacteria. The data presented suggest that J217 be classified as Flavobacterium oceanosedimentum sp. nov.

Two mycoplasmas, from a group of five strains previously recovered from ground squirrels, were found to be similar in biochemical and serological properties. The organisms were able to ferment glucose and other carbohydrates, did not hydrolyze arginine or urea, produced a film-and-spot reaction, and could grow at temperatures from 30 to 37°C. The organisms required cholesterol for growth. The two strains were shown to be serologically distinct from 64 Mycoplasma species or unclassified serotypes. On the basis of these findings and of other morphological, biological, and serological properties of the organisms, it is proposed that mycoplasmas with these characteristics belong to a new species, Mycoplasma citelli. Strain RG-2C (= ATCC 29760) is the type strain.

Thirty-five nitrogen-fixing, hydrogen-oxidizing bacteria, all members of Cory-nebacterium autotrophicum Baumgarten, Reh, and Schlegel 1974, and including the type strain of this species, were compared with 28 strains of coryneform bacteria by numerical taxonomy methods. The nitrogen-fixing hydrogen bacteria formed a well defined cluster; their similarity to the other strains tested was low, however. Furthermore, the chemotaxonomic characters of these strains excluded them from the coryneform bacteria. Therefore C. autotrophicum was reclassified, following the keys of Bergey’s Manual of Determinative Bacteriology (8th ed.) as a species of the family Azotobacteraceae. Although taxonomically close to Beijerinckia and Derxia, the nitrogen-fixing, hydrogen-oxidizing bacteria are regarded as representing a new genus, for which we propose the name Xanthobacter. C. autotrophicum Baumgarten, Reh, and Schlegel is transferred to the new genus as Xanthobacter autotrophicus (Baumgarten et al.) comb. nov.