Zentralblatt für Bakteriologie Mikrobiologie und Hygiene: I. Abt. Originale C: Allgemeine, angewandte und ?kologische Mikrobiologie最新文献

Three hundred and thirty strains of citrate-fermenting lactobacilli were isolated from lamb stomach, lamb rennet paste, sheep milk and Pecorino Romano cheese.

Fifty-two representative strains belonging to four physiological groups were checked for their genetic relationship using the DNA-DNA hybridization test. Most of the hetero-fermentative strains, isolated from lamb stomach and lamb rennet paste belonged to Lactobacillus reuteri, while the others were found to be related to L. fermentum. The homofermentative citrate-fermenting lactobacilli, isolated mainly from Pecorino Romano cheese, shared high levels of genetic homology with L. plantarum. Only one strain was found to be similar to L. casei.

A preliminary classification of strains from several species of streptococci by DNA/rRNA hybridization showed several sub-groups. The largest sub-group divided into two clusters (1) included S. bovis, S. uberis and S. salivarius and (2) S. agalactiae, S. dysgalactiae, S. acidominimus and S. thermophilus. S. lactis and S. cremoris formed a different sub-group as did S. faecalis and S. faecium, S. raffinolactis and most species of viridans streptococci did not associate with any of the sub-groups. The technique was of assistance in linking strains with unusual phenotypic properties to named species.

Corynebacterium ilicis (Mandel, Guba and Litsky) differs to such an extent from the type species of Corynebacterium, Cor. diphtheriae (Kruse), that it cannot be retained in this genus. It is suggested that Cor. ilicis be reclassified in the genus Arthrobacter as Arth. ilicis comb. nov.

The resistance of 81 Rhizobium strains and 11 Agrobacterium strains to 16 antibiotics was investigated. Most strains were resistant even to high concentrations of lincomycin.

All the strains of the species Rhizobium meliloti, Rhizobium phaseoli, Rhizobium japonicum and the genus Agrobacterium reacted relatively homogeneously to all the antibiotics, unlike Rhizobium trifolii, Rhizobium leguminosarum and Rhizobium spp.

The majority of the fast-growing species of Rhizobium tested was found to be resistant to > 32 μg/ml penicillin and to < 1 μg/ml tetracyclin. On the other hand, most of the slow-growing species of Rhizobium were susceptible to penicillin concentrations < 16 μg/ml while they were resistant to tetracyclin concentrations > 1 μg/ml.

The majority of the Agrobacterium strains tested were resistant to streptomycin concentrations > 32 μg/ml, allowing them to be distinguished from strains of R. meliloti which were rarely resistant to such high concentrations.

Of 477 strains of lactobacilli isolated from municipal sewage 30 homofermentative, L( + )-lactic acid producing strains containing meso-diaminopimelic acid in their cell walls could not be allotted to one of the so-far described species when in a first attempt of identification a limited number of key criteria was applied. Taxonomic studies including DNA-DNA hybridization led to the description of two new species, namely Lactobacillus sharpeae sp.nov. and Lactobacillus agilis sp.nov.

On the basis of phenetic and chemotaxonomic criteria three new species of bacteroides from the oral cavity are described. Bacteroides buccalis sp.nov., Bacteroides denticola sp. nov. and Bacteroides pentosaceus sp. nov.

The type-strain of Streptomyces ramuloses Ettlinger et al. ETH 17653 (= ATCC 19802) was studied by phase contrast microscopy, scanning electron microscopy and transmission electron microscopy. During germination the spores may pass through three stages: darkening, swelling and emergence of the germ tube. In poor media swelling is not always essential for the development of germ tubes. The hyphae of primary mycelium are phase dark. Sporulating hyphae of aerial mycelium are phase bright, relatively thick and show in scanning electron microscopy a slightly roughened surface due to the surrounding sheath.

The spores develop in short, straight or slightly curved chains forming a monopodially branched system. Sporulation starts with the formation of simple, solid septa dividing the sporogenous hyphae into compartments of spore size. The spore wall is formed de novo. At first a thin but electron-dense layer is deposited to which a more electron-transparent layer is added. During spore wall formation the material of the septa and the parent hyphal wall begins to autolyze. Mature spores evidence only slight remnants of septa forming connections from spore to spore.

The morphology of the spore chains and the fine structure of the sporulation process confirms the exceptional position of Streptomyces ramulosus.

Ammeline is a common product of the degradation of s-triazine herbicides. The biodegradation of ammeline by 165 microbial strains has been investigated. 95% of all strains tested were able to degrade ammeline to ammelide and 35% could degrade ammelide further to cyanuric acid which was accumulated in the growth medium. Only strain CBS 472.48 of Sporothrix schenckii was capable of metabolizing ammeline slowly to carbon dioxide and ammonium. The highest specific rate for ammeline degraded to cyanuric acid was 3.3 μkat × kg dry weight of cells⁻¹. The deamination of ammelide was usually the rate-limiting step. The enzymes degrading ammeline to cyanuric acid were formed constitutively. Ammonium and urea, however, caused repression of enzyme synthesis, and ammonium caused a slight inhibition of the ammeline-degrading enzyme activity. Efficient degradation of ammeline to carbon dioxide and ammonium (0.4 μkat × kg dry weight of cells⁻¹) could be achieved using a mixed culture of a pseudomonad, strain 123 B, and a fungus, Sporothrix schenckii strain 6.2.

The genome sizes of a number of strains belonging to 5 different well-established bacterial species were determined in 8 to 45 replicate experiments by means of the initial renaturation rate method. Published data on 7 other bacterial species were also examined. It appears that the genome sizes of different strains within a single species are either identical or show no great differences. The average half range of the distribution is 10% of the average genome molecular weight and does not exceed 18%. Most species evidence one or two clusters of strains with identical genome size and a few strains differing distinctly as to their genome size.

A new species of the genus Ectothiorhodospira is described isolated from alkaline soda lakes of the Wadi Natrun in Egypt. In most of its properties it resembles the recently described Ectothiorhodospira halochloris, which had been isolated from similar lakes of the same area. The new species, Ectothiorhodospira abdelmalekii, has spiral-shaped cells with 0.9-1.2 μm diameter, it is polarly flagellated with sheated flagella, has lamellar photosynthetic membrane stacks, possesses bacteriochlorophyll b as the main photosynthetic pigment, and has a DNA base composition of 63.3–63.8 mol% G + C. Photolithotrophic growth with sulfide or elemental sulfur as electron donors is the predominant mode of life. During sulfide oxidation to sulfate, elemental sulfur is accumulated outside the cells. Acetate, pyruvate, fumarate and succinate are photoassimilated. The properties of E. halochloris and E. abdelmalekii are compared.