PubMed Health⌕ Search

Biomedical subjects

H W Ackermann

Publications and source records attributed to H W Ackermann.

At least 19 recordsLinked to original sources
PubMed1992

Frequency of morphological phage descriptions.

Bacteriophages are listed by morphotypes and host genera. At least 4.007 phages, belonging to 13 virus families, have been described since 1960. About 3,850 phages (96%) are tailed and 154 phages (4%) are cubic, filamentous, or pleomorphic. Siphoviridae or phages with long noncontractile tails constitute 60% of tailed phages. Phages are found in over 100 bacterial genera including archaebacteria and rickettsiae. Their distribution is very uneven and probably reflects the evolutionary history of bacteria.

Bacteria↗
PubMed1992

The species concept and its application to tailed phages.

A recently proposed polythetic definition of virus species appears easily applicable to bacteriophages. Criteria for classification of tailed phages are evaluated. Morphology, DNA homology, and serology are the most important criteria for delineation of species, but no single criterion is satisfactory. Dot-blot hybridization and seroneutralization may suggest false relationships by detecting common sequences in the DNA of otherwise unrelated phages. Species of tailed phages can be defined by a combination of morphology and DNA homology or serology. A procedure for identification of novel phages is outlined. Phage names should include elements of host names.

Bacteriophages↗
PubMed1992

Characteristics and diffusion in the rabbit of a phage for Escherichia coli 0103. Attempts to use this phage for therapy.

A bacteriophage for Escherichia coli 0103 was isolated during a study on E. coli diarrhoea in intensive breeding units of rabbits. The phage had an isometric head and a short tail and resembled coliphage N4 (Podoviridae). It had a very narrow host range and seemed to be specific for serogroup 0103, suggesting that it might be used for preliminary identification of E. coli strains of this serogroup instead of the usual slide agglutination. In view of its possible use as a therapeutic phage, we investigated its dissemination in rabbit organs after oral administration. The phage persisted in the spleen for at least 12 days. However, in vivo studies showed that this phage and a mixture of more virulent phages for E. coli 0103 were ineffective in preventing disease in rabbits inoculated with an enteropathogenic strain of E. coli 0103.

Animals↗
PubMed1992

Large-scale blood substitute production using a microfluidizer.

Microfluidization has been tested as a way to disperse phospholipids in aqueous hemoglobin solutions. Spherical and stable liposomes of 2 to 3 microns were obtained. Lipid incorporation (up to 85%) and hemoglobin encapsulation (up to 15%) in liposomes have been improved with respect to previous investigations. However, results show that a more efficient dispersion system using lower concentrations of lipid is required to obtain a high liposome hemoglobin concentration (limited actually to 150 g/l) and an economically and biologically suitable process for artificial blood production at large scale.

Blood Substitutes↗
PubMed1989

A new bacteriophage of Corynebacterium glutamicum isolated from swine waste.

A bacteriophage for Corynebacterium glutamicum strain LP-6 was isolated from swine waste. It belongs to the Siphoviridae family or Bradley morphologic group B, has a narrow host range, and is sensitive to chloroform and resistant to carbon tetrachloride. The phage is unstable (96% inactivation) in swine waste stored for 4 months at 22 C. The DNA has a molecular weight of approximately 20 Md, cohesive ends, and numerous restriction endonuclease sites. The phage differs from other known C glutamicum phages.

Animals↗
PubMed1988

Morphology of Brochothrix thermosphacta phages.

Twenty-one Brochothrix thermosphacta phages were examined by electron microscopy. They had isometric heads and contractile or long and noncontractile tails, and were grouped into three species belonging to the Myoviridae (species A19) or Siphoviridae (species NF5 and BL3) families of tailed phages. Species A19 has highly characteristic morphological features and resembles well-known phages of Bacillus, Lactobacillus, Staphylococcus and Streptococcus, indicating phylogenetic relationships between these phages as well as their hosts.

Bacteriophages↗
PubMed1987

Bacteriophage taxonomy in 1987.

Ten families and eight genera have been approved by the International Committee on Taxonomy of Viruses (ICTV) and include at least 230 species. A new basic phage group has been found in Archaebacteria. Over 2700 phages are tailed; about 130 are cubic, filamentous or pleomorphic. Their distribution provides insights into phage origin.

Bacteriophages↗
PubMed1979

DNA base composition, nature of intracellular DNA, morphology, and classification of bacteriophages infecting Micrococcus luteus.

Ten bacteriophages infecting Micrococcus luteus have been characterized. All phages contain double-stranded DNA, of 64.3--73.5 mol% guanine plus cytosine (GC). The DNA of phage N7 has the highest GC content reported for any bacterial virus. No unusual bases have been found. The intracellular replicating DNAs of six phages are covalently closed circular molecules. All 10 phages have isometric, probably icosahedral, heads and long, flexible, noncontractile tails and can be sorted into two morphological groups based on size and presence or absence of a collar. Host-range studies indicate six host-range groups.

Bacteriophages↗
PubMed1979

Characterization of two Salmonella newport bacteriophages.

Salmonella newport phages 16--19 and 7--11 have very long heads and are members of two rare and so far little-known phage groups. Both produce various morphological aberrations. Preparations of phage 7--11 contain numerous polyheads and about 0.4% short heads belonging to nine size classes. In addition, one giant phage particle was observed. The head of phage 7--11 seems to be an icosahedron which became elongated by adding successive rows of subunits. Phages 16--19 and 7--11 have buoyant densities in CsCl of 1.43 and 1.48 g/mL and particle weights of 103 and 204 x 10(6) respectively. Both viruses contain double-stranded DNA, internal proteins, and sugars. Phage 16--19 contains 46.5% DNA of 35 x 10(6) molecular weight, and glucose. Phage 7--11 contains 47.5% DNA of 108 x 10(6) molecular weight, and mannose. Base compositions of phage and S. newport DNAs were determined from buoyant densities, melting point, and acid hydrolysis. Phage 16--19 contains 5.4% 5-methylcytosine.

Base Composition↗
PubMed1978

Partial characterization of a cubic Bacillus phage.

Partial characterization of a cubic Bacillus phage. Can. J. Microbiol. 24: 986--993. Phage Bam35 is an icosahedron of about 63 nm in diameter. It has a double capsid with spikes at the vertices, and a tail which seems to appear upon nucleic acid ejection. The phage contains DNA and, probably, lipids which seem to be located in the inner coat. The phage is Bacillus-specific, UV- and lipase-resistant, and sensitive to heat, chloroform, and ether. The latent period is 50 min and the burst size is 39. Page Bam35 belongs to a new virus group which includes a phage of B. anthracis and four phages of gram-negative bacteria harboring drug-resistance plasmids.

Bacillus thuringiensis↗
PubMed1978

[Phage-like particles produced by Clostridium tetani].

Two C. tetani strains used for toxin production spontaneously produce two varieties of phage-like particles with isometric heads. Type A has a contractile tail, whereas type B shows a non-contractile tail with a long, wavy tail fiber. No relationship between the presence of these particles and the amount of toxin produced was found.

Bacteriophages↗
PubMed1978

[The classification of Agrobacterium and Rhizobium phages (author's transl)].

All phages studied are tailed, belong to six morphological groups, and are classified by morphological and serological properties and by physico-chemical parameters of the virion and its nucleic acid. Four species of Agrobacterium and 12 species of Rhizobium phages are described, and their relationship with enterobacteria phages discussed. They include 68 viruses, whereas 60 poorly known phages have not been classified.

Bacteriophages↗
PubMed1978

[Study of lysogeny in Bacillus thuringiensis and B. cereus].

Forty-eight strains of Bacillus thuringiensis and 12 strains of B. cereus were treated with ultraviolet light and mitomycin C. The former agent was the more effective inducer. Bacillus thuringiensis produces at least seven different phage particles with long, non-contractile tails. The frequencies of lysogeny and polylysogeny are 83 and 25% respectively. Morphologically defective phages occur in 25% of strains, whereas five of them produce low molecular-weight bacteriocins. One strain of B. cereus harbors "killer-particles." There is no apparent correlation between the presence of phage-like particles, phage senstivity, and serotypes, biotypes, or the origin of B. thuringiensis strains.

Bacillus cereus↗