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PubMed1980

Transfer of group A streptococcal pyrogenic exotoxin production to nontoxigenic strains of lysogenic conversion.

Production of group A streptococcal pyrogenic exotoxins (SPE) type A and C was transferred from toxigenic streptococcal strains to nontoxigenic strains by lysogeny. Lysogens were tested for SPE with Ouchterlony immunodiffusion on Todd-Hewitt agar plates; toxin diffusing from isolated colonies reacted with specific hyperimmune antisera to SPE. Phage prepared from strains T25(3) (T12gl) and 3GL16, both yielding SPE type A, formed plaques on T25(3) (NONLYSOGENIC) lawns. Over 90% of the colonies picked from the plaque centers yielded A toxin, suggesting SPE type A was transferred by lysogenic conversion. SPE type C formation was transferred to nontoxigenic strains T25(3) and K56 with supernatant fluids from mitomycin C-induced cultures of CS112, producing SPE types B and C. All lysogens tested were positive for SPE type C, indicating that C toxin induction also was transferred by lysogenic conversion. SPE type B formation was not transferable by lysogeny with the strains tested.

Bacterial Toxins↗
PubMed2000

Sunlight-induced propagation of the lysogenic phage encoding cholera toxin.

In toxigenic Vibrio cholerae, the cholera enterotoxin (CT) is encoded by CTXPhi, a lysogenic bacteriophage. The propagation of this filamentous phage can result in the origination of new toxigenic strains. To understand the nature of possible environmental factors associated with the propagation of CTXPhi, we examined the effects of temperature, pH, salinity, and exposure to direct sunlight on the induction of the CTX prophage and studied the transmission of the phage to potential recipient strains. Exposure of cultures of CTXPhi lysogens to direct sunlight resulted in approximately 10,000-fold increases in phage titers. Variation in temperature, pH, or salinity of the culture did not have a substantial effect on the induction of the prophage, but these factors influenced the stability of CTXPhi particles. Exposure of mixed cultures of CTXPhi lysogens and potential recipient strains to sunlight significantly increased both the in vitro and in vivo (in rabbit ileal loops) transduction of the recipient strains by CTXPhi. Included in these transduction experiments were two environmental nontoxigenic (CTXPhi(-)) strains of V. cholerae O139. These two O139 strains were transduced at high efficiency by CTXPhi, and the phage genome integrated into the O139 host chromosome. The resulting CTXPhi lysogens produced biologically active CT both in vitro and in rabbit ileal loops. This finding suggests a possible mechanism explaining the origination of toxigenic V. cholerae O139 strains from nontoxigenic progenitors. This study indicates that sunlight is a significant inducer of the CTX prophage and suggests that sunlight-induced transmission of CTXPhi may constitute part of a natural mechanism for the origination of new toxigenic strains of V. cholerae.

Animals↗
PubMed1976

Specialized transduction of D-serine deaminase genes: formation of lysogens that yield high lambda-d dsd/lambda ratios and formation of a dimeric lambda-d dsd.

We have obtained two classes of double lysogens that on induction yield higher titers of lambda-d dsd transducing phage than of helper phage. One class was obtained by lysogenization of strain EM6116 (dsddelta attlambdadelta HfrC) with lambda-dsd type 2 (dsdC+ dsdO+ dsdA+, head-tail substitution). In the absence of either a normal attlambda or the homology of a chromosomal dsd region, the transducing phage integrated at other sites, at least one of which, in strain EM6177, is near the origin of HfrC. On induction, strain EM6177 yields a phage burst of 20 to 50 with a lambdadsd:lambda ratio of 10(4):1. The asnychronously high yield of lambda dsd is attributed to an efficiency of excision greater than that of lambda. The other class was obtained by lysogenization of strain EM1407 (dsdA attlambda+) with lambda-dsd type 2 (dsdO6 dsdA, partial deletion of dsdC). The DNA of mature lambda-dsd type 2 is a complete dimer. It lacks nearly all the phage late genes and b2 and carries about five bacterial genes. It could not be packaged as a monomer but is just within the packaging size limit as a dimer. Models for the derivation of these lambda dsd phages and the high-yielding lysogens are presented.

Chromosome Mapping↗
PubMed1987

Lysogenic conversion of Salmonella typhimurium bacteriophages A3 and A4 consists of O-acetylation of rhamnose of the repeating unit of the O-antigenic polysaccharide chain.

Lysogenization of Salmonella typhimurium with either of the bacteriophages A3 and A4 results in O-acetylation of the L-rhamnose residues of the O-polysaccharide chain of the lipopolysaccharide of the bacterial cell envelope. The O-acetyl group is found on both O-2 and O-3 of the L-rhamnosyl residues. This lysogenic conversion prevents the adsorption of the A3 and A4 phages and also greatly reduces the rate of adsorption of phage P22 to the O-polysaccharide chain as measured by binding studies with whole bacteria. Isolated lipopolysaccharide from A3- and A4-lysogenized bacteria was also inefficient in inactivating these phages: the concentration required for 50% inactivation was 10,000-fold higher than that for lipopolysaccharide from S. typhimurium not lysogenized by any A phage. Binding of phages A3 and A4 is accompanied by hydrolysis of the alpha-1,3 linkage between rhamnose and galactose in the tetrasaccharide repeating unit of the O-polysaccharide. Phage hydrolysis generates saccharides of various lengths, the majority being dodecasaccharides, i.e., equivalent to three repeating units. It is surmised that O-acetylation of the rhamnosyl residue interferes with phage A3, A4, and P22 infection by preventing binding to and hydrolysis of the O-polysaccharide chain, the initial step in the phage infection cycle. The new O-acetyl-rhamnose entities did not elicit specific antibodies in rabbits in accordance with earlier experiences. The O-acetylation of O-2 and O-3 of rhamnose is a new, hitherto unknown, modification of the O-polysaccharide chain of S. typhimurium.

Acetylation↗
PubMed1988

Intermediates in bacteriophage Mu lysogenization of Escherichia coli him hosts.

Characterization of a putative intermediate in the Mu lysogenization pathway is possible in a variant Escherichia coli himD strain which exhibits greatly diminished lysogen formation. In this strain, most infecting Mu genomes form stable, transcribable, nonreplicating structures. Many of these genomes can be mobilized to form lysogens by a second Mu infection, which can be delayed by at least 100 min. This intermediate structure can be formed in the absence of Mu A or B function. We suggest that the inferred intermediate could be the previously reported protein-linked circular form of the Mu genome. Providing Mu B function from a plasmid enhances Mu lysogenization in this him strain, and the enhancement is much greater when both Mu A and B functions are provided.

Adsorption↗
PubMed1962

Lysogenic conversion in Pseudomonas aeruginosa.

Holloway, B. W. (University of Melbourne, Victoria, Australia) and G. N. Cooper. Lysogenic conversion in Pseudomonas aeruginosa. J. Bacteriol. 84:1321-1324. 1962.-When Pseudomonas aeruginosa strain 1 is lysogenized with phage D3, it loses the ability to adsorb this phage. This loss is attributed to an alteration of the somatic antigens of the bacterium, initially detected by differences in the opsonizing capacity of normal mouse serum for the lysogenic and nonlysogenic strains. Antigenic analysis has suggested that there is a difference in only one antigen between the lysogenic and nonlysogenic organisms.

Animals↗
PubMed1963

PHAGE ISOLATED FROM LYSOGENIC BACILLUS ANTHRACIS.

Buck, C. A. (Kansas State University, Manhattan), R. L. Anacker, F. S. Newman, and A. Eisenstark. Phage isolated from lysogenic Bacillus anthracis. J. Bacteriol. 85:1423-1430. 1963.-Bacillus anthracis cultures (a total of 311) were obtained from several laboratories throughout the world; 139 of these were screened for the presence of lysogenic organisms. Phage particles were obtained from 25 of these cultures. The host range of five of these phages, plus that of phage gamma, was tested against 246 B. anthracis cultures plus 64 other Bacillus strains. The results show that phage might be useful in the identification of B. anthracis, although two non-B. anthracis cultures were lysed. Also, the diversity of host range indicated that a phage-typing scheme for epidemiological studies might be feasible. Several lysogenic cultures were sensitive to the phage that they liberated, indicating a dismune phenomenon. Also, some lysogenic cells liberated two distinct kinds of phage. Other phage properties, such as morphology, plaque morphology, burst time, and serological relationship, are described.

Bacillus↗
PubMed1976

Lysogenization of Escherichia coli by bacteriophage Lambda: complementary activity of the host's DNA polymerase I and ligase and bacteriophage replication proteins Q and P.

When bacteriophage lambda DNA replication is blocked by mutation in phage genes O or P, the efficiency of lysogenization drops to a very low value unless high multiplicities of infecting phage are used. Our results show that even at high multiplicity, lambda O or P mutants cannot efficiently lysogenize some hosts that are defective in either DNA polymerase I or DNA ligase. Covalent closure of infecting DNA molecules, a preliminary step for insertion according to Campbell's model and an obvious candidate for this lysogenization defect, appears to occur normally under our conditions. In addition, prophage excision as measured by the frequency of curing O- and P- lysogens seemed normal when tested in the poll- strain. These results suggest that the Escherichia coli enzymes DNA polymerase I and ligase, and phage proteins O and P, are able to provide some complementary activity whose function is required specifically for prophage integration.

Coliphages↗
PubMed1978

Lysogenic conversion in Klebsiella pneumoniae: system which requires active immunity regulation for expression of the conversion phenomenon.

We have previously described Klebsiella pneumoniae MirM7b, which, although stably lysogenic for the inducible and nondefective phages FR2 and AP3, is not immune to superinfection by these same viruses. MirA12b, a strain which is lysogenic for FR2 and AP3 and immune to superinfection, has been derived from MirM7b. The sensitivity of this strain and that of the nonimmune parent to several bacteriophages have been compared in this work. It has been found that, whereas MirM7b is sensitive to coliphages P1, T3, T7, and phiI, MirA12b is fully resistant to all of them. It is shown that phages FR2 and AP3 convert Klebsiella strains to resistance to coliphage P1 and coliphages T3, T7, and phiI, respectively, and cause loss of surface antigens in lysogenic cells. To determine such a conversion, both FR2 and AP3 require expression of immunity to superinfection. This explains the differences that exist between MirM7b and MirA12b in both phage sensitivity and surface antigens. Hypotheses are presented to explain the peculiar need for an active superinfection repressor to express lysogenic conversion.

Antigens, Bacterial↗
PubMed1971

Influence of transformability on the formation of superinfection double lysogens in Haemophilus influenzae.

Superinfection of growing (nontransformable) cells of defectively lysogenic strains of Haemophilus influenzae with wild-type or with mutant phage HP1 resulted in a number of double lysogens and a small number of monolysogens with altered prophage. The double lysogens were identified by analysis of their monolysogenic segregants and by examining their deoxyribonucleic acid in certain test crosses. The results indicate that the majority had been formed by insertion of the infecting phage genome within the resident prophage. Superinfection of transformable bacteria gave rise to cells with altered prophages (presumably transformants) and to double lysogens which had gained or lost wild-type prophage loci.

Anti-Bacterial Agents↗
PubMed1984

Isolation of nonlysogenic bacteria from lambda-lysogenized strains using antibiotic-resistant phage.

A simple and efficient method for obtaining nonlysogenic bacteria from lambda-lysogenized strains using phage with an inserted antibiotic-resistant plasmid is described. When the lysogenic culture is infected with antibiotic-resistant phage, single non-lysogenic cells are lysogenized, isolated on selective medium, and cured of phage during incubation at 37 degrees C.

Anti-Bacterial Agents↗
PubMed2006

Inhibitory effects of anti-SARS traditional Chinese medicines on the UV irradiation of lambda-lysogen.

By using lambda-lysogen as a model, the inhibitory effects of anti-severe acute respiratory syndrome (SARS) traditional Chinese medicines (TCMs) prescription I on the UV irradiation were investigated in this present study. It was found that the prescription I possessed obvious inhibitory effects on the UV induction of lambda-lysogen, the inhibitory rate reaching 83.87%. Among five medicinal herbs prescribed in that formula, Herba Patriniae, Radix Astragali and Radix Glycyrrhizae played important roles. When these three herbs were eliminated from the recipe separately, the inhibitory effects were prominently decreased. If only one of these five medicinal herbs was added into the medium of lambda-lysogen, the inhibitory rates ranged from 27.0% approximately 45.0%. By electron spin resonance (ESR) detection, we found that the prescription I, Herba Patriniae and other main herbs in that recipe, could quench effectively the free radicals generated in the process of lambda-lysogenic cells by UV. These results provide a novel idea for further studying the pharmacology of TCM and exploring the mechanism of SARS virus infection.

Bacteriophage lambda↗
PubMedDate not supplied

Effects of mixed-function oxidase and aflatoxin B1 on lysogenic and indicator strains of Bacillus subtilis.

The present study was conducted to determine the effects of metabolized aflatoxin B1 (via a mammalian liver mixed-function oxidase system) and native aflatoxin B1 upon induction of bacteriophage in Bacillus subtilis and growth of B. subtilis. A lysogenic strain of B. subtilis (BDS-1, phi 105) and an indicator strain of this species (DBS-1) were utilized in the present experiment. Lysogenic cultures were incubated for various lengths of time in the presence of either native or metabolized toxin, and plaque-forming units were determined. Identical experiments were conducted with the indicator strain and colony-forming units were determined. At a native toxin concentration of 25 micrograms/ml of medium, the maximum number of plaque-forming units was induced in lysogenic cells. However, when cells were incubated in the presence of aflatoxin B1 and mixed-function oxidase, neither plaque-forming units nor colony-forming units could be detected from lysogenic or indicator cells, respectively. This organism is apparently much more susceptible to inhibition of cellular replication than to lysis via bacteriophage induction. Thus, from the present study and from previously reported research, differences in susceptibility to native and metabolized aflatoxin B1 exist among species of Bacillus.

Aflatoxin B1↗
PubMed1984

Prophage induction by liver microsomal metabolites of aflatoxin B1 in lysogenic Pseudomonas aeruginosa.

Microsomal metabolites of aflatoxin B1 (AFB1) causing induction of prophage in lysogenic strain of Pseudomonas aeruginosa SM was studied. Reduction of culture turbidity was determined at various concentrations of toxin. The effect of the toxin was also studied on deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and protein synthesis. AFB1 at the concentration of 50 micrograms/ml reduced initial turbidity to approximately 90% in 4 h. DNA synthesis stopped completely in the first hour but reappeared due to induction of the temperate phage. Soon after induction both RNA and protein synthesis continued but later little or no net synthesis of these macromolecules occurred. Plaque forming units (pfu) were increased approximately 90 times at 2 h as compared to the control. Testing of the effect of AFB1 on the non-lysogenic, sensitive strain demonstrated that although there was no significant decrease in culture turbidity at 50 micrograms/ml concentration of AFB1, DNA synthesis stopped completely within 1 h, while RNA and protein synthesis were increasing throughout the test interval. It has been concluded that the liver microsomal fraction of AFB1 caused induction of prophage in lysogenic cells and inhibited DNA synthesis significantly in non-lysogenic cells.

Aflatoxin B1↗
PubMed1997

[Lysogenic conversion as a factor influencing tolerance to vancomycin in Staphylococcus aureus].

The standard, non-lysogenic, bacteriophage-free S. aureus NCTC 8325-4 strain was lysogenized with 15 different, obtained in our laboratory staphylokinase-converting bacteriophages belonging to serological groups A, B and F. MIC and MBC of vancomycin as well as the ratio of MBC to MIC were evaluated for all 15 lysogenic derivatives. The obtained results were compared with those for maternal strain. In the case of eight strains the ratio MBC/MIC showed the presence of tolerance to vancomycin (MBC/MIC > or = 32). Four of the vancomycin-tolerant derivatives were lysogenized with bacteriophages belonging to the serological group A, two were members of group B and two belonged to group F.

Anti-Bacterial Agents↗
PubMed2002

Three recently acknowledged Escherichia species strikingly differ in the incidence of bacteriocinogenic and lysogenic strains.

The incidence of bacteriocinogeny and lysogeny was followed in bacteria of 3 recently acknowledged species of the genus Escherichia: E. hermanii, E. vulneris and E. fergusonii. Almost all of the strains examined were of human origin. In 30 strains of E. hermanii no one was found bacteriocinogenic while 57% were lysogenic, in 30 strains of E. vulneris none was found to be bacteriocinogenic and only 10% were lysogenic, and in 50 strains E. fergusonii 12% were bacteriocinogenic and 40% lysogenic. From the 6 bacteriocinogenic strains of E. fergusonii, 3 were producers of colicin E1, 2 of colicin Ib and 1 of colicin Ia. In addition, 3 E. fergusonii strains produced aerobactin.

Bacterial Proteins↗
PubMed1999

The primary immunity determinant in modulating the lysogenic immunity of the filamentous bacteriophage cf.

Bacteriophage cf is the first single-stranded DNA phage that has been shown to set up a stable lysogenic state with its genome integrated into the host chromosome. From the isolation and characterization of a virulent mutant, cf-tv2, we report the first investigation into the mechanisms of the immunity established by the filamentous bacteriophage. The mutation in cf-tv2 enables the phage to produce plaques on lawns of cf lysogenic cells. The mutation was defined as a 49-nucleotide deletion located in a 0.59 kb NcoI/KpnI fragment of cf replicative form DNA. Two messages, cM1 and cM2, transcribed from the immunity region of wild-type cf but in opposite directions, were detected. In cf-tv2, the 49-nucleotide deletion abolishes cM2 transcription. The primer extension assay suggests a possible RNA-RNA interaction directed by base-pairing of the cM1 and cM2 RNAs. A frameshift mutation of the open reading frame ORF 165, encoded by cM2, resulted in a 10(5) plating efficiency on the cf lysogen. These observations suggest that both RNA-RNA interaction and repressor protein inhibition are involved in the mechanism of cf immunity. A model is proposed for the regulation of cf immunity.

Amino Acid Sequence↗
PubMed1977

Induction of lambda prophage and of mutations to streptomycin resistance in separate small fractions of a lysogenic derivative of Escherichia coli B/r by very low doses of ultraviolet light.

The number of induced mutations to streptomycin resistance is compared at doses of ultraviolet (UV) light between 0.2 and 6.4 J/m2 in a Uvr- (excision-deficient) derivative of E. coli B/r, strain WU, and in its lambda lysogen, strain WU(lambda). At UV doses up to about 1 J/m2, which converts about 5% of the lysogenic population into enfective centers, no difference is observed in the number of mutations to streptomycin resistance produced by the two strains. It is concluded that the capacity to produce UV-induced mutations is not coupled with lysis due to the induction of lambda prophage at low doses of UV radiation. At UV doses above 1 J/m2, the number of mutatants detected in the lysogenic strain decreases appreciably compared to the number detected in the nonlysogen, and is only about 10% as high at UV doses of 3 J/m2 and higher, doses which cause maximal induction of prophage. The results are compatible with the operation of a common "all-or-none" induction signal resulting in expression of UV-inducible functions at high UV doses, but not at low doses.

Coliphages↗