Electron microscopical characterization of newly isolated Rhizobium lupini bacteriophages

Eight strains of Rhizobium lupini bacteriophages newly isolated from compost soil were studied in the electron microscope. The phage particles investigated had either long contractile, long non-contractile, or short non-contractile tails. The wedge-shaped appearance of short phage tails is discussed.

Unrelatedness of temperate Bacillus subtilis bacteriophages SP02 and phi105

SPO2 and phi105 are temperate Bacillus subtilis bacteriophages which have been suggested to belong to a cluster of related bacteriophages. In the present work, we show that SPO2 does not complement any of the 11 essential genes known in phi105 and that the phages do not recombine. Deoxyribonucleic acid (DNA)-DNA hybridization shows less than 10% homology between SPO2 and phi105 DNA. DNA synthesis in phi105 shows a greater dependence on host functions than does SPO2 DNA synthesis. Growth of phi105 but not of SPO2 is inhibited by the uracil analogue 6-(p-hydroxyphenylazo)-uracil. Infection of a DNA polymerase-deficient strain of B. subtilis with SPO2 leads to an increase in DNA polymerase activity in crude extracts, whereas no such increase is found after infection of this strain with phi105. It is concluded that SPO2 and phi105 are unrelated bacteriophages.

Isolation of a polyvalent bacteriophage for Escherichia coli, Klebsiella pneumoniae, and Aerobacter aerogenes

A lytic bacteriophage isolated from sewage was found to attack strains of Aerobacter aerogenes, Escherichia coli, and Klebsiella pneumoniae, but not members of the genera Salmonella, Proteus, and Serratia. The phage, designated phimp, contained deoxyribonucleic acid with a 50% guanine plus cytosine ratio and a molecular weight of 23.1 x 10(6) daltons. Single-step growth experiments of phimp plated at 37 C on A. aerogenes A2 gave a mean latent period of 20 min, an average burst size of 103 plaque-forming units/infected cell, and an average adsorption rate constant of 3 x 10(-10) ml/min. Electron microscopy of phimp revealed a phage with a flexible tail (165 nm long and 6 nm wide). The phage head had a hexagonal outline (62 nm in diameter).

Intergroup lysis and transduction by streptococcal bacteriophages

Bacteriophages from streptococci of groups A, E, and G lysed streptococci distributed among serogroups A, C, G, H, and L; propagated in some, but not all, of these; and transduced streptomycin resistance within group A or (by A phages only) from group A to group G streptococci.

Deoxyribonucleic acid bacteriophage of methanomonas methylovora

A new bacteriophage of low guanine plus cytosine (GC) content for Methanomonas methylovora has been isolated. Phage deoxyribonucleic acid contained 32 to 35% GC.

Study of two bacteriophages of Bacillus stearothermophilus strain NCA1518

Studies of bacteriophages GH5 and GH8 of Bacillus stearothermophilus strain NCA1518 revealed that their properties were sufficiently different from known phages and from each other to indicate that each was a different entity, although no major deviation was demonstrated.

Isolation of Mycoplasmatales viruses and characterization of MVL1, MVL52, and MVG51

Eleven Mycoplasmatales viruses are now known. Burst size, burst time, sensitivity to ultraviolet and the host range of three viruses that were studied are different. However, all three are naked, rod-shaped particles of similar size. Plaque morphology and the isolation of immune cells suggest that both virulent and nonvirulent infections are possible.

Isolation and properties of suppressor-sensitive mutants of Bacillus subtilis bacteriophage SP02

Suppressor-sensitive mutants of Bacillus subtilis phage SPO2 were isolated and classified into 18 cistrons. A linear genetic map was constructed. The genes controlling early functions of phage development were clustered near the CI gene which may produce phage repressor.

Comparative studies with tox plus and tox minus corynebacteriophages

The characteristics of nine inducible temperate corynebacteriophages designated alpha(tox+), beta(tox+), P(tox+), gamma(tox-), pi(tox+), K(tox-), rho(tox-), L(tox+), and delta(tox+) have been compared. Virion morphology and ability to recombine genetically with the well-studied phage beta(tox+) have been correlated with other properties of the phages, and the distribution of the genetic marker tox+ among related and relatively unrelated corynebacteriophages has been analyzed. The immunity specificity, host range, and plaque morphology of each phage were determined. The phages can be separated into five groups with different immunity specificities. Each type of host range previously recognized in mutants of phage beta(tox+) was present in one or more of the phages included in the present study, and the phages were found to produce plaques of several different morphological types. Representative phages with each of the five types of immunity specificity were further characterized with respect to virion morphology, ability to recombine with phage beta(tox+), latent period, average burst size, and neutralization by homologous and heterologous antiphage sera. All of these phages have polyhedral heads and long slender tails, but two distinct morphological types were distinguished by the sizes and proportions of the components of the virions. Only phages of the same morphological type as beta(tox+) were capable of genetic recombination with beta(tox+), but morphological similarity between phages was not sufficient to insure interfertility. The phages which recombined with beta(tox+) resembled one another in plaque morphology, latent period, and average burst size, whereas phages which failed to recombine with beta(tox+) differed in these characteristics. The phages capable of genetic recombination with beta(tox+) were found to differ from each other in immunity specificity, host range, neutralization by antiphage sera, and toxinogenicity. Thus, these latter characteristics are of limited value in establishing the extent of relatedness between corynebacteriophages. The genetic marker tox+ was not consistently correlated with any other property of the corynebacteriophages analyzed in this study. The most striking finding regarding the distribution of the tox+ marker is its presence both in beta(tox+) and delta(tox+), phages which fail to recombine genetically and which differ in virion morphology. The presence of the tox+ marker in genetically unrelated corynebacteriophages poses many questions concerning the origin(s) of tox+ and the evolution of the phage-host interactions which determine the ability of corynebacteria to synthesize diphtherial toxin.

New bacteriophage of Haemophilus influenzae

Some properties of a newly isolated Haemophilus influenzae bacteriophage are described. The phage is morphologically distinct from previously described H. influenzae phages.