- Volume 27, Issue 2, 1977

The degree of binding was determined between deoxyribonucleic acid (DNA) preparations from nocardias and uracil-labeled DNA from four reference strains of Nocardia asteroides. The N. asteroides strains fell into three DNA homology groups, one of which contained the type strain of Nocardia farcinica ATCC 3318. The relevance of the genetic data to the structure of the N. asteroides taxon is discussed. The nucleotide composition of the DNA preparations from the N. asteroides strains fell between 64 and 68 mol% guanine plus cytosine.

The 181 bacteria classified as Proteus rettgeri biovar 5 considered to be a group intermediate to P. rettgeri and Providencia stuartii were found, in all cases, to possess O-specificities characteristic of Providencia O-serovars. Isolates of the intermediate group showed biochemical reactions characteristic of Prov. stuartii except for positive reactions in tests for urea hydrolysis. The reassignment of the intermediate strains (P. rettgeri biovar 5) to Prov. stuartii is advocated.

The second cooperative numerical taxonomic analysis of Runyon group IV rapidly growing mycobacteria was facilitated by combining the results of 12 individual participants, each performing one or more of the selected tests by his or her own choice of method. The 177 characters were coded for analysis and the matching matrix was generated. Eight of nine clusters which were defined in this investigation were of previously named species. The recognized clusters were as follows: Mycobacterium flavescens, M. vaccae, M. chitae, M. thermoresistibile, and M. smegmatis. One large cluster, designated “M. parafortuitum complex” was noted which contained strains representative of taxa earlier identified as M. parafortuitum, M. diernhoferi, M. aurum, M. neoaurum, and a cluster of strains of unnamed species. It is suggested that segregation of species or subspecies within this complex not be attempted at this time.

The isolation of a new mycoplasma from pooled lower-alimentary-tract tissues of a cow and the isolation of serologically and otherwise similar organisms from the lower alimentary tract, feces, or urogenital tract of other cows are described. The first isolate, designated Ilsley, was used as a reference strain, and two clones were examined in characterization tests. The Ilsley strain has the essential cultural, morphological, and biological properties of mycoplasmas (including a typically low deoxyribonucleic acid base ratio of 26.4 mol% guanine plus cytosine) but exhibited some unusual features of minor taxonomic importance. These included the ability to metabolize both glucose and arginine, resistance to polyanethol sulfonate but not digitonin, and an unusual morphology, as indicated by electron microscopy, with flask- or club-shaped cells and some distinctive terminal structures. The Ilsley strain was shown to be serologically distinct from 57 Mycoplasma nomenspecies (14 from bovine and 43 from human and other animal sources), including species with similar biochemical and cultural characteristics. On the basis of the above findings, it is proposed that this new strain and the other, similar ones belong to a new species, Mycoplasma alvi. Strain Ilsley (= NCTC 10157) is the type strain.

Cell membranes from the two mycoplasmas Acholeplasma laidlawii and Spiroplasma citri differ greatly in solubility properties and were, therefore, used as models in this investigation. The membranes were isolated and solubilized with different neutral and anionic detergents. The solutions were analyzed by crossed immunoelectrophoresis in the presence of the corresponding detergent. In the case of A. laidlawii membranes, good results were obtained with the anionic detergent sodium deoxycholate (DOC) and with the neutral detergents Triton X-100 and Tween 20. However, in the case of S. citri membranes, reliable results were obtained only with DOC. These findings indicate that it is preferable to use DOC as solubilizing agent in a standardized procedure of analyzing membrane antigens from different mycoplasmas by crossed immunoelectrophoresis. In experiments with membrane antigens from one mycoplasma and membrane antiserum from another mycoplasma, in order to save time and antisera it is recommended first to run a double diffusion and, if the result is positive, the sample can be further analyzed by crossed immunoelectrophoresis.

Strains representing the mycolic acid-containing taxa Nocardia, Mycobacterium, Gordona, Corynebacterium, Bacterionema, and the “rhodochrous” complex were analysed for polar lipids by two-dimensional, thin-layer chromatography; diphosphatidylglycerol and phosphatidylinositol were found in all strains and phosphatidylethanolamine was absent only in extracts of Corynebacterium and Bacterionema. Mono- and diacyl phosphatidylinositol dimannosides were present in all Nocardia, Mycobacterium, Corynebacterium, and rhodochrous strains and in the single strain of Gordona aurantiaca examined; Bacterionema and strains of the other Gordona species had only a monoacyl phosphatidylinositol dimannoside. Phosphatidylglycerol was present in substantial amounts in extracts of two strains of Bacterionema matruchotii and in reduced proportions in strains of several other species. Unidentified glycolipids were detected in the lipids of a majority of the organisms investigated.

The polar lipids of Actinomadura dassonvillei, Actinomadura madurae, and Actinomadura pelletieri were analysed by two-dimensional thin-layer chromatography. A. madurae and A. pelletieri had a simple pattern consisting essentially of diphosphatidylglycerol, phosphatidylinositol, and monoacyl phosphatidylinositol dimannoside, but A. dassonvillei strains contained diphosphatidylglycerol, phosphatidylglycerol, a lipid which co-chromatographed with phosphatidylcholine, and a chromatographically mobile unknown phospholipid. Two A. dassonvillei strains had substantial proportions of uncharacterised glycolipids and phosphoglycolipids. Low proportions of lipids co-chromatographing with, and having the same staining reactions as, phosphatidylethanolamine, phosphatidylinositol, and diacyl phosphatidylinositol dimannoside were detected in several strains of A. dassonvillei.

Several authors have suggested that Flavobacterium pectinovorum Dorey 1959 should be removed from the genus Flavobacterium and that it might be a Cytophaga species. An extensive study of the morphological, physiological, biochemical, and antimicrobial lytic properties of the holotypic strain NCIB 9059 (ATCC 19366) of F. pectinovorum has revealed that it is more properly classified as Cytophaga johnsonae Stanier 1947. The guanine-plus-cytosine ratio of 33 mol% agrees with the range reported for C. johnsonae (30 to 35 mol%).

Forty-seven strains of yellow-pigmented, non-fermentative, gram-negative, rod-shaped bacteria isolated from clinical specimens (14 strains), the hospital environment (20 strains), and miscellaneous sources (13 strains) were characterized with respect to 68 phenotypic tests. The results, along with those of the same 68 tests carried out on 51 reference strains that represented species of Pseudomonas and six other genera of gram-negative bacteria, were analyzed by numerical taxonomic methods. Twenty-nine of the 47 yellow-pigmented strains, including two strains of Weaver group IIk, biotype 1, formed a homogeneous phenetic group (within-group similarity: 93.4% SG). The group consisted of strictly aerobic, heterotrophic rod-shaped bacteria. Cells were motile by means of a single polar flagellum. Only a few of the cells were actively motile in nutrient broth cultures, so this characteristic was often difficult to demonstrate. The strains were homogeneous in their susceptibilities to antimicrobial agents, and the mean guanine-plus-cytosine. content of the deoxyribonucleic acids from 13 of the isolates was 64.9 ± 1.4 mol%. The 29 strains conformed to the general characteristics of the genus Pseudomonas. The reasons for excluding the strains from Xanthomonas are discussed. We consider these strains to represent a new species, for which we propose the name Pseudomonas paucimobilis. The type strain of the new species is CL1/70 (=NCTC 11030). The remaining 18 yellow-pigmented isolates were unclassified except for two strains which corresponded to a Flavobacterium sp. (King group IIb).

The type strains of the three currently recognized species of the genus Microcyclus Ørskov 1928 (M. aquaticus Ørskov, strain ATCC 25396; M. major Gromov, strain BKM 859; and M. flavus Raj, strain ATCC 23276), together with strains apparently belonging to each species, were examined to determine their taxonomic relationships. There were many differences between the type strains in their morphological and physiological characteristics as well as in the guanine-plus-cytosine (G+C) contents of their deoxyribonucleic acids (DNAs). Therefore, we propose to split the genus Microcyclus into three genera, each containing a single species. M. aquaticus, the type species of Microcyclus, remains as the only species in the genus. It is characterized by the formation of cellular rings which are produced when the ends of the curved cells overlap. It is nonpigmented and is respiratory in its metabolism; the G+C content of its DNA ranges from 66.3 to 68.4 mol%. M. flavus ATCC 22376 and three similar strains were found to possess characters in agreement with those given in the original description of Spirosoma linguale, and they were placed in that species. The name M. flavus Raj 1970 thus becomes a later subjective synonym of Spirosoma linguale (Eisenberg 1891) Migula 1894. This species is characterized by the formation of wavy and coiled filaments, yellow pigmentation on Microcyclus-Spirosoma (MS) agar, and respiratory metabolism. The G+C content of its DNA ranges from 51.0 to 52.9 mol%. Strain DSM 74 is designated as the neotype strain of S. linguale. M. Major BKM 859 and one similar strain were placed in a new genus, Flectobacillus. F. major (Gromov) comb, nov., the type species, is composed of rods which are straight to curved, the degree of curvature varying among individual cells within a culture. The cells may form long, sinuous filaments and rings. Colonies on MS agar are pale pink to rose-colored. Metabolism is respiratory, and the G+C content of its DNA ranges from 39.5 to 40.3 mol%. The type strain of F. major is strain BKM 859.

An unusual mesophilic bacillus was isolated from soil, and a cleaned spore preparation of this organism showed extreme resistance to dry heat (D125°C = 139 h, D130°C = 54 h, D135°C = 24 h, D140°C = 13 h, D145°C = 8 h, D145°C = 2.5 h; where D = time at temperature effecting 90% reduction in viable count); and relative sensitivity to moist heat (D80°C = 61 min). The biochemical tests, exterior and interior spore morphology, and growth characteristics of this organism do not fit those of any of the presently described species of bacteria. Consequently, we regard this organism as belonging to a new species, for which we propose the name Bacillus xerothermodurans. The type strain of this species has been deposited in the American Type Culture Collection as ATCC 27380.

The exposure of Myxococcus stipitatus to long-wave ultraviolet light results in a yellowish-green fluorescence. This character will aid in the identification of this species.

A description has been given of a new variety of yeast associated with the ants of the group Formica rufa L. Torulopsis apis var. galacta differs from T. apis by its spheroidal cell shape and its inability (or very weak ability) to assimilate raffinose and to grow in vitamin-free medium. In addition, it was found that the type strain T. apis produces primitive pseudomycelium.