- Volume 29, Issue 4, 1979

Mycobacterium flavum strain 301 (= Deutsche Sammlung von Mikroorganismen 338), a hydrogen-utilizing bacterium, is capable of fixing molecular nitrogen and resembles other nitrogen-fixing hydrogen bacteria. However, it is clearly different in many characters from other strains of M. flavum (Orla-Jensen) Jensen (syn.: Microbacterium flavum Orla-Jensen). It does resemble strains of Xanthobacter Wiegel et al. with respect to cell wall composition, production of carotenoid pigments, carbon source utilization pattern, and deoxyribonucleic acid (DNA) base composition (69 mol% guanine + cytosine). Strain 301 is here regarded as belonging to a new and distinct species, for which the name Xanthobacter flavus is proposed. Strain 301 is the type strain of this species. X. flavus differs from Xanthobacter autotrophicus, the only other species in this genus to date, in several respects, and the DNA-DNA hybridization between X. flavus and X. autotrophicus is only 25%.

A new leptospiral strain, Compton 699, was found to belong to serovar semaranga of the Semaranga serogroup. Antigenic analysis revealed the presence in this strain of a new main antigen which was also found in the other serovars of the same sero-group.

Among the several thousand bifidobacteria of our collection, 244 strains from the feces of rabbits and suckling pigs, the rumen of cattle, the feces of breast-and bottle-fed infants, the feces of calves, and from sewage are recognized by means of deoxyribonucleic acid (DNA)-DNA hybridization (competition filter method) as belonging to four new, distinct DNA homology groups. Twenty reference DNA preparations from the type strains of the currently known species or from reference strains of the homology groups of Bifidobacterium were used for comparison. The phenotypic traits which distinguish these four groups from previously described species of the genus Bifidobacterium include gross morphology, fermentation characteristics, guanine plus cytosine content of the DNA, the interpeptide bridge of the cell-wall peptidoglycan, and the transaldolase and 6-phosphogluconate dehydrogenase isozyme pattern (by starch gel electrophoresis). The four groups are named and described as new species of the genus Bifidobacterium: B. cuniculi, B. choerinum, B. boum, and B. pseudocatenulatum. The type strains of these species are RA93 (=ATCC 27916), SU806 (=ATCC 27686), RU917 (=ATCC 27917), and B1279 (=ATCC 27919), respectively.

The electrophoretic patterns of the transaldolases and 6-phosphogluconate dehydrogenases (6PGD) of 1,206 strains, each belonging to one of 24 named species of the genus Bifidobacterium, were determined by means of starch-gel electrophoresis. All of these strains were previously assigned to species on the basis of their deoxyribonucleic acid homology relationships and were selected so as to include all known phenotypes and habitats. Fourteen electrophoretic forms of transaldolase and 19 of nicotinamide adenine dinucleotide phosphate-dependent 6PGD were identified and numbered. Each strain displayed one band for each enzyme. Glucose-grown cells of the B. pullorum strains and of most of the B. dentium strains were devoid of detectable levels of 6PGD. The zymograms of more than 60% of the strains studied were species specific. Nearly half of the other strains had significant overlapping of transaldolase and 6PGD patterns, and they were assigned therefore to species on the basis of an additional marker, 3-phosphoglyceraldehyde dehydrogenase production, the results of which are not reported here in detail. Of the species studied, B. asteroides exhibited the greatest variability in electrophoretic types of both transaldolase and 6PGD. Correlations between electrophoretic data, deoxyribonucleic acid homology relationships between the species, and ecology are discussed.

Polynucleotide sequence relationships among strains of Peptococcus saccharolyticus were assessed by analysis of deoxyribonucleic acid-deoxyribonucleic acid homo and heteroduplexes with endonuclease S1. The results showed that P. saccharolyticus strains isolated from different subjects form a very tight group, with deoxyribonucleic acid homology levels ranging between 93 and 100%. Physiological tests of 23 strains included 30 different substrates. Results were remarkably uniform. All 23 strains grew better anaerobically with added H2 and CO2 than aerobically. However, colony size was greater on blood agar but not Trypticase soy (BBL Microbiology Systems, Cockeysville, Md.)-yeast extract agar with an atmosphere of 4% O2 with added H2 and CO2 than with anaerobic incubation. The data suggest that these strains are sufficiently closely related to justify their inclusion in a single discrete species, but their appropriate generic classification remains to be resolved.

Flavobacterium aquatile (Frankland and Frankland) Bergey et al. 1923, the type species of the genus Flavobacterium, was originally described as motile and later defined as a nonmotile glucose fermenter. The neotype strain of F. aquatile, ATCC 11947, is flagellated, spreads in semisolid agar, and produces oxidative acidity from glucose. Flavobacterium meningosepticum King 1959 was reported to be nonmotile and both oxidative and fermentative. The type strain of F. meningosepticum, ATCC 13253, is flagellated, spreads in semisolid agar, and produces oxidative acidity from glucose. The flagellar morphologies of the two strains are similar. The genus Flavobacterium should not include species which ferment glucose.

A simple, reproducible technique with potential taxonomic application was developed for the rapid detection of rhodanese activity in gram-negative and gram-positive bacteria. The method requires suspension of the growth from three colonies in a solution of lysozyme and ethylenediaminetetraacetic acid for 60 min. After cell lysis, the presence of rhodanese activity is determined colorimetrically by measuring the amount of thiocyanate formed from thiosulfate and potassium cyanide by use of ferric nitrate. By this technique, a survey of 411 bacterial strains revealed the presence of rhodanese in all test strains of Escherichia coli, Pseudomonas aeruginosa, Acinetobacter, Bordetella, Shigella, and Citrobacter. No activity was detected in Salmonella, Klebsiella, Enterobacter, Serratia, or Proteus species. Randomly selected strains which did not exhibit rhodanese activity were confirmed to be rhodanese-negative by assay of mechanically disrupted cells harvested from 500 ml of growth medium.

The deformation test and the metabolism inhibition test are simple and highly sensitive serological tests capable of revealing antigenic differences among spiroplasmas. Spiroplasma strains from plant and invertebrate hosts were compared in a combined deformation-metabolism inhibition test conducted in microtiter plates. Four major serological groups of spiroplasmas were recognized on the basis of deformation-metabolism inhibition tests. Group 1 was the Spiroplasma citri complex, comprised of isolates from plants, insects, and ticks. This group was provisionally divided into four serological subgroups. Subgroup 1 included the S. citri type strain (Maroc) and spiroplasmas isolated by Kondo and associates from cactus and lettuce. The second subgroup contained three corn stunt spiroplasma isolates. Subgroup 3 comprised 2 Spiroplasma strains isolated from honey bees by T. B. Clark. Subgroup 4 consisted of a single isolate (277F) from ticks. Each of these subgroups showed some serological cross-reactions with one or more of the other subgroups. Three other serologically distinct Spiroplasma clusters were observed. The suckling mouse cataract agent and an additional rabbit tick isolate (TP-2) were placed in group 2. Group 3 spiroplasmas included T. B. Clark’s isolates (OBMG and BNR1) from flowers of magnolia and tulip trees. The fourth distinct serological group was represented by the uncultivated sex ratio spiroplasmas from Drosophila

A new genus, Xenorhabdus, is created to accommodate large, gram-negative, rod-shaped, facultatively anaerobic, entomopathogenic bacteria which are intimately associated with entomogenous nematodes. The normal habitat of these bacteria is the intestinal lumen of nematodes or the body cavity of host insects into which they have been introduced by the nematodes. The genus is placed in the family Enterobacteriaceae since the bacteria possess most of the important characteristics of this family. Xenorhabdus differs from other genera of Enterobacteriaceae in large cell size, failure to reduce nitrates to nitrites, intimate association with entomogenous nematodes, entomopathogenesis, and immunological characteristics. The type species is Xenorhabdus nematophilus (Poinar and Thomas) comb. nov. (synonym: Achromobacter nematophilus Poinar and Thomas). Xenorhabdus luminescens sp. nov., a bioluminescent, entomopathogenic bacterium isolated from the intestinal lumen of an entomogenous nematode, Heterorhabditis bacteriophora, is also described. In addition to their immunological differences, the two species are dissimilar in that X. luminescens is positive for bioluminescence and catalase activity, whereas X. nematophilus is not. The type strain of X. nematophilus is ATCC 19061, and that of X. luminescens is strain Hb (= ATCC 29999).

Strains of a new type of rapidly growing, scotochromogenic mycobacterium have been isolated repeatedly from sphagnum vegetation of moors in south Sweden and the Atlantic coastal area of Norway. These strains split urea and succinamide, hydrolyze Tween 80, produce acid from glucose, fructose, mannitol, rhamnose, sorbitol, and trehalose, and grow on a medium with fumarate, succinate, citrate, malonate, oxalate, propanol, or hippurate as the single carbon source. Furthermore, they possess acid phosphatase and putrescine oxidase activities, degrade salicylate, and metabolize iron. Additional properties of these strains are presented. The internal similarity of the strains, as determined by numerical taxonomy methods, as 94.97 ± 3.42%. A comparison with 21 species (clusters) of rapidly growing mycobacteria is also presented. The production of mycolic acid by these strains and their micromorphology confirm that they belong to the genus Mycobacterium. The strains have unique lipid and immunodiffusion patterns and form special sensitins. These strains are considered as belonging to a new species of nonpathogenic, rapidly growing mycobacteria for which we propose the name Mycobacterium komossense. Strain Ko 2 is the type strain of M. komossense; a culture of this strain has been deposited in the American Type Culture Collection under the number 33013.

Six strains of gram-negative, polarly flagellated, antibiotic-producing marine bacteria that synthesize an orange, noncarotenoid pigment were submitted to an extensive phenotypic characterization. All of them had properties characteristic of the genus Alteromonas. Two strains were closely related to Pseudomonas piscicida. The others could be considered as members of a new species for which the name Alteromonas aurantia is proposed. The type strain of A. aurantia is strain 208 (= ATCC 33046 = NCMB 2052).

Eleven strains of pink-pigmented bacteria, isolated from the leaf surface of Lolium perenne (perennial rye grass), were compared with six marker strains and 50 pink-pigmented isolates from a variety of habitats. The organisms were examined for 146 unit characters, and the data were analyzed by the simple matching and Jaccard coefficients and the average-linkage algorithm. The Lolium strains formed a single, well-defined cluster. These isolates were gram-negative, oxidative rods which were motile by means of one to three polar flagella; the guanine-plus-cytosine content of the deoxyribonucleic acid of a representative strain was 65.8 ± 0.5 mol%. The organisms were classified in the genus Pseudomonas but could not be assigned to any previously defined species. A new species, Pseudomonas mesophilica, is proposed for these organisms; the type strain is A47 (= ATCC 29983 = ICPB 4095).

A total of 95 strains of moderately to extremely halophilic bacteria, either from culture collections or freshly isolated, were subjected to taxonomic analysis by the computer method. The culture collection strains were examined in the initial phase of the study, and the fresh isolates were examined later. Three major groupings of these organisms were evident: a group of rodlike halophiles, a group of halotolerant, rod-shaped bacteria, and a less morphologically homogeneous, but taxonomically distinct, cluster of halophilic cocci. The rodlike halophiles could be further subdivided into one cluster containing strains of Halobacterium cutirubrum, which, on initial isolation, are capable of growth on media containing 8% salt when incubated at elevated temperatures, and another cluster containing strains of Halobacterium salinarium, which have a minimum requirement for 15% salt irrespective of the temperature of incubation. NRC 34002 and NRC 34001 are proposed as the neotype strains of Halobacterium salinarium and Halobacterium cutirubrum, respectively. The group of halophilic cocci appeared to be less homogeneous, i.e., were less uniform in character frequency of occurrence. Halococcus morrhuae is judged to be the correct name for the halophilic cocci. Results of the taxonomic analyses also indicated that at least two, and perhaps three, biovars comprise H. cutirubrum. A comparative study of the halophiles and a sample of 48 strains of halotolerant streptococci, staphylococci, and micrococci did not reveal any significant interrelationships. The moderate halophiles included in this analysis appear to be taxonomically distinct from the extreme halophiles. Results of lipid and pigment analyses accumulated for the halophilic bacteria support the taxonomic conclusions.

With respect to Shigella flexneri, serovar 6 should be transferred to S. boydii; serovar 5 should be divided into two subserovars, 5a and 5b, with antigenic formulas V:(4) and V:7, respectively; and serovar 3 should contain only two subserovars, 3a-III:(3,4),6 and 3b-III:(3,4),6,7,8. Concerning the six provisional Shigella serovars, serovar 2000-53 should be removed from the genus because it belongs to the genus Escherichia, the position of serovar 1624-54 is still under consideration, serovars 3873-50 and 3341-55 should be placed in S. dysenteriae as serovars 11 and 12, respectively, and serovars 2710-54 and 3615-53 should be considered as members of S. boydii serovars 16 and 17, respectively.

The proposal by Henriksen and Bøvre in 1968 to transfer Neisseria catarrhalis, N. caviae, and N. ovis to the genus Moraxella has been supported by recent genetic and chemotaxonomic studies. The proposal by B. W. Catlin (Int. J. Syst. Bacteriol. 20:155-159) in 1970 to transfer N. catarrhalis to a new genus, Branhamella, has not been followed by similar proposals for the other two coccal species, although occasionally they have been referred to informally as members of Branhamella. As a compromise so as to facilitate communication between adherents to these different taxonomies, it is presently proposed to divide the genus Moraxella Lwoff 1939 emend. Henriksen and Bøvre 1968 into two subgenera—subgenus Moraxella (Lwoff 1939) Bøvre 1979 for the six rod-shaped species (Moraxella lacunata, M. bovis, M. nonliquefaciens, M. osloensis, M. phenylpyruvica, and M. atlantae) and subgenus Branhamella for the three coccal species. Strain 199/55 (= ATCC 33078 = NCTC 11227) is here proposed as the neotype strain of Moraxella (Branhamella) ovis (Lindqvist 1960) Henriksen and Bøvre 1968, Bøvre 1979.

In 1973 the author proposed the name Mycobacterium farcinogenes for the causal agent of farcy in African bovines. Two varieties (subspecies) of this species were recognized by the author: M. farcinogenes subsp. tchadense and M. farcinogenes subsp. senegalense. Because the former is the type subspecies of the species, its name should have been M. farcinogenes subsp. farcinogenes. It is now proposed that these subspecies constitute two separate and distinct species: M. farcinogenes Chamoiseau and M. senegalense (Chamoiseau) comb. nov. IEMVT 75 (= NCTC 10955) and IEMVT 378 (= NCTC 10956) are herein designated the type strains of these two species, respectively.

Exception is taken to the classification of cyanophytes as bacteria. The fact that cyanophytes can now be grown in pure culture does not necessarily mean that their nomenclature should be dealt with by the Bacteriological Code, which, contrary to the Botanical Code, permits viable, pure cultures to serve as representatives of type strains, or that consequently they are bacteria. The question of the true nature of cyanophytes (i.e., bacterial or algal) should be discussed by both botanists and microbiologists, and the matter should perhaps be referred to the International Union of Biological Sciences for a ruling.