Concurrent morphological and chemical events in Staphylococcus aureus exposed to penicillin

Disruption and lysis as well as accumulation of cell-wall precursor material have been demonstrated in several strains of Gram-positive cocci as results of the action of penicillin. The concurrence of these phenomena in typically penicillin-sensitive bacteria lends further support to the hypothesis that penicillin exerts its antibiotic action through interference with the formation of cell walls.

Lysis of brucellae by the combined action of glycine and a lysozyme-like agent from rabbit monocytes

Ralston, Doris J. (University of California, Berkeley), B. S. Baer, and S. S. Elberg. Lysis of brucellae by the combined action of glycine and a lysozyme-like agent from rabbit monocytes. J. Bacteriol. 82:342-353. 1961.-An acid-extractable lytic material was obtained from rabbit monocytes. It acts on a substrate in the walls of brucellae and has properties similar to egg-white lysozyme. Brucella melitensis strain Rev Is is completely resistant to this agent and also to crystalline lysozyme, but when the cells are exposed to sufficient amounts of glycine, the surface is rendered susceptible to these lytic agents. Rough type Rev Is cells are more susceptible than smooth, and the virulent B. melitensis strain 6015 is most resistant.

Lysis of Escherichia coli by sulfhydryl-binding reagents

Schaechter, M. (College of Medicine, University of Florida, Gainesville) and K. Santomassino. Lysis of Escherichia coli by sulfhydryl-binding reagents. J. Bacteriol. 84:318-325. 1962-Washed suspensions of gram-negative rods were lysed by low concentrations of some sulfhydryl-binding and oxidizing reagents, but not by reducing agents. Some kinetic aspects of this phenomenon were studied with p-chloromercuribenzoate and Escherichia coli B/r. Structures resulting from the action of this reagent consisted of impure cell walls. These could be purified by treatment with trypsin. Cell walls prepared mechanically and cell membranes obtained by lysing protoplasts were not overtly affected by this chemical.

Enzymatic properties of a phage-induced lysin affecting group A streptococci

Doughty, C. C. (University of Illinois College of Medicine, Chicago) and James A. Hayashi. Enzymatic properties of a phage-induced lysin affecting group A streptococci. J. Bacteriol. 83:1058-1068. 1962.-Phage-induced lysis of group C streptococci releases into the medium a lysin which completely lyses group A streptococci. Partial purification of the lytic activity yields 47% of the original activity with a 17-fold purification. The activity was assayed by observing lysis of group A streptococci under standard conditions. The optimal pH range for lysis is from 6.0 to 6.7. A monovalent cation requirement satisfied by Na(+), K(+), or Li(+) is shown by the lysin. Lysis is stimulated by ethylenedi-aminetetraacetic acid (EDTA), chlortetracycline, streptomycin, and penicillin. It is inhibited by p-hydroxymercuribenzoate (pHMB), and the inhibition is reversed by cysteine. Other inhibitors include ristocetin A and specific antisera against the lysin. Isolated group A streptococcal cell walls are partially lysed by massive amounts of lysin. This partial lysis is not affected by EDTA, pHMB, chlortetracycline, streptomycin, or ristocetin A. It is concluded that the enzymatic process of lysis of isolated cell walls is not identical to the more complex process resulting in lysis of intact cells.

THE CELL-BOUND ALPHA-AMYLASES OF STREPTOCOCCUS BOVIS

1. The cell-bound alpha-amylase of Streptococcus bovis has been isolated from other carbohydrases in the cell extract by chromatography on DEAE-cellulose. The enzyme has been compared with the extracellular alpha-amylase produced by this organism. 2. The two amylases had similar action patterns on amylose, the main product being maltotriose with smaller amounts of maltose and a little glucose. 3. The cell-bound amylase hydrolysed maltopentaose and maltohexaose at a similar rate to the hydrolysis of amylose. Maltotetraose was hydrolysed six times more slowly, and maltotriose 280 times more slowly, than amylose. 4. Studies with end-labelled maltodextrins revealed that the cell-bound alpha-amylase preferentially hydrolysed the third linkage from the non-reducing end, liberating maltotriose. The linkage at the reducing end of maltotriose was more easily hydrolysed than the other. 5. Egg-white lysozyme and the extracellular enzymes of Streptomyces albus lysed the cell walls of Streptococcus bovis, releasing amylase into the medium. In the presence of 0.6 m-sucrose 10% of the maximal amylase activity was released by lysozyme. Suspension of the spheroplasts in dilute buffer caused the rupture of the cytoplasmic membrane and the liberation of amylase. 6. A sensitive method for determining the ability of amylases to degrade starch granules is described.

DENSITY-GRADIENT PATTERNS OF STAPHYLOCOCCUS AUREUS CELLS AND CELL WALLS DURING GROWTH AND MECHANICAL DISRUPTION

Huff, Eskin (National Institute of Allergy and Infectious Diseases, Bethesda, Md.), Harriet Oxley, and Carol S. Silverman. Density-gradient patterns of Staphylococcus aureus cells and cell walls during growth and mechanical disruption. J. Bacteriol. 88:1155-1162. 1964.-Procedures capable of rapid disruption of Staphylococcus aureus cells with optimal release of intact cell walls were investigated. This search was implemented by observation of the flotation patterns of cells and subcellular particulate matter after centrifugation in a cesium chloride density gradient. A quantitative evaluation of the light-scatter throughtout the gradient was achieved by transfer of the entire density gradient into an optical cell with wedge-shaped cross section. When this cell was photographed under indirect illumination, each band of light-scattering material appeared on the negative as a shaded curve, with an area proportional to amount of that material present. A series of photographs of known amounts of cells and cell walls was used to estimate the amounts of these materials in mixtures of the two occurring during mechanical disruption. With the methods employed, time studies established the optimal time for release of cell walls as 5 min in a Braun shaker. The use of sucrose gradients in the further purification of cell walls, and chemical analysis of the isolated walls, are described.

TEMPERATURE-SENSITIVE MUTANTS OF BACILLUS SUBTILIS BACTERIOPHAGE SP3. II. IN VIVO COMPLEMENTATION STUDIES

Nishihara, Mutsuko (University of California, Los Angeles), and W. R. Romig. Temperature-sensitive mutants of Bacillus subtilis bacteriophage SP3. II. In vivo complementation studies. J. Bacteriol. 88:1230-1239. 1964.-A plate-spotting procedure was used in initial attempts to group the temperature-sensitive Bacillus subtilis phage SP3 mutants by complementation. The results obtained did not show any clear patterns of reactions among the mutants. Crosses were, therefore, repeated in broth at a temperature of 49 C, which greatly reduced the extent of replication of each mutant type alone. The data on mixed infections indicated that there was a minimum of six complementation groups. Of the 12 isolates, 7 did not seem to complement with each other; the rest complemented with each other and with the seven noncomplementing mutants. There was a positive correlation between the complementation reaction of a pair and the recovery of wild-phenotype phages from a 49 C broth lysate. The relative proportion of phages capable of forming wild-phenotype plaques on plates incubated at 46 C to the total number of plaque-forming units was higher in a lysate of a mixed infection with two mutants than in lysates of each mutant alone. Moreover, this frequency was higher for a mixed lysate made at 49 C than for a lysate of the same two mutants made at 37 C. These observations suggested that genetic recombination might occur at 49 C, and that the increased recovery of wild-phenotype phages in lysates made at this temperature might be due to a selective advantage for these phages. Recombination experiments at 37 C with some complementing pairs gave frequencies of 2.0 to 4.8%. The ratio of wild-phenotype revertants to total phages in the stock lysates used for these crosses at 37 C was less than 10(-6). The noncomplementing mutants were not conclusively shown to be nonidentical.

IMMUNOGENIC SUBSTANCES IN CULTURE FILTRATES AND LYSATES OF PASTEURELLA TULARENSIS

Hatch, Melvin T. (University of Utah, Salt Lake City), and Paul S. Nicholes. Immunogenic substances in culture filtrates and lysates of Pasteurella tularensis. J. Bacteriol. 88:566-573. 1964.-Culture filtrates and lysates of Pasteurella tularensis were tested for immunogenicity in mice subsequently infected with either strain 425 or 425 F4G. The efficacy of the vaccines varied with dosage and was significantly dependent upon methods of preparation. The optimal procedures for the production of an immunologically potent vaccine included: (i) aging the cultures after growth under partial anaerobiosis at 37 C, and (ii) inactivating the cells with phenol or formaldehyde. An unusual "survival phenomenon" was suggested when mice were administered large doses of cell-free vaccines and subsequently large doses of moderately virulent P. tularensis. The data indicated that the filtrates and lysates elicited an immune response sufficient to protect against an active infection with strains 425 or 425 F4G, and that the challenge dose per se stimulated an enhanced immunity. Furthermore, this survival phenomenon was demonstrable when immunized mice were subsequently given massive doses of strain 425 and challenged with approximately 1,000 ld(50) of the fully virulent strain Schu. On the basis of our data, we have hypothesized that the protective antigens were released into the suspending medium as a result of alterations in the permeability of cells undergoing either complete or partial enzymatic degradation. We believe that the envelope antigens were released from the cell by mechanisms analogous to those causing leakage of intracellular constituents in cells maintained at an incubation temperature in an unfavorable growth environment.

STAPHYLOCOCCAL SENSITIZATION: SPECIFIC BIOLOGICAL EFFECTS OF PHAGE K ON THE BACTERIAL CELL WALL IN LYSIS-FROM-WITHOUT

Ralston, Doris J. (University of California, Berkeley). Staphylococcal sensitization: specific biological effects of phage K on the bacterial cell wall in lysis-from-without. J. Bacteriol. 85:1185-1193. 1963.-Phage K, shown previously to sensitize staphylococcal-wall mucopeptide to the action of a phage-induced enzyme, virolysin, was found to act in a specific manner in that its sensitizing effects were restricted to chemical linkages affected by three staphylococcal lysins. These caused an immediate lysis, whereas egg-white lysozyme, which could also digest the wall mucopeptide, exerted variable effects, even when in the absence of phage it produced some lysis. Evidence was presented that the K(1) normal cell autolysin and the K phage virolysin could act synergistically with lysozyme on phage-sensitized cells, and that any effects observed with lysozyme were due to the simultaneous presence of trace amounts of these staphylococcal lysins. None of a series of lysozymelike agents from sea urchins, marine sepunculids, and from rabbit peritoneal histiocytes caused accelerated lysis of phage-sensitized cells, although like lysozyme they showed a slow lysis of phage-free living cells. Other enzymes which did not reduce the turbidity of sensitized cells included agents specific for intracellular components (proteins, lipids, nucleic acids), and enzymes, as decarboxylase, alkaline phosphatase, d-amino oxidase, and hyaluronidase. These results suggested that the main effects of the phage in sensitization were limited to areas of the cell wall involved in protection against the action of the staphylococcal lysins.

PROTOPLAST LYSIS AND INHIBITION OF GROWTH OF BACILLUS LICHENIFORMIS BY BACITRACIN

Snoke, John E. (University of California, Los Angeles), and Neal Cornell. Protoplast lysis and inhibition of growth of Bacillus licheniformis by bacitracin. J. Bacteriol. 89:415-240. 1965.-The growth of Bacillus licheniformis is inhibited by bacitracin, the antibiotic which the organism itself produces. The effect of the antibiotic is confined to the early growth phase of the organism. Bacitracin will produce a rapid lysis of protoplasts of B. licheniformis and Micrococcus lysodeikticus. The lytic process requires cadmium or zinc ions, and the rate and extent of lysis depends upon the amount of bacitracin and metal ion added. Although B. licheniformis and M. lysodeikticus differ markedly in their sensitivity to bacitracin, the protoplasts from these two organisms are equally susceptible to lysis by the antibiotic.

DRUG RESISTANCE OF ENTERIC BACTERIA. IV. ACTIVE TRANSDUCING BACTERIOPHAGE P1 CM PRODUCED BY THE COMBINATION OF R FACTOR WITH BACTERIOPHAGE P1

Kondo, Eiko (Gunma University, Maebashi, Japan), and Susumu Mitsuhashi. Drug resistance of enteric bacteria. IV. Active transducing phage P1 CM produced by the combination of R factor with phage P1. J. Bacteriol. 88:1266-1276. 1964.-During an investigation of the transduction of R factors with phage P1, a phage lysate capable of transducing the character of chloramphenicol resistance (CM(r)) in extremely high frequency was obtained. The transduction of the CM(r) character with the lysate was consistently accompanied by lysogenization with the phage used for transduction. This lysate exhibits no beneficial effect with normal P1, and no effect is produced by decreasing the multiplicity of infection. A single infection with the phage allows the formation of plaques as well as CM(r) lysogenic cells at the center of the plaque. Both the transducing and plaque-forming activities of the lysate were lost by neutralization with anti-P1 phage serum, and its absorption to the host bacteria was enhanced by the addition of Ca(++). Thus, it was concluded that a derivative of P1 phage (P1 CM) was isolated which had not only the ability to transduce the CM(r) character but also the capacity to form plaques; i.e., the CM(r) gene of R factor is specifically associated with the genome of phage P1. No detectable differences were noted between P1 CM and normal P1 phage in density-gradient analyses in CsCl, in stability of lysogenization, in ability to transduce chromosomal markers, and in the mode of induction from lysogenic cells by ultraviolet irradiation. The instance of transduction of the CM(r) character described here may also be considered as an example of lysogenic conversion, in the sense that the alteration in CM(r) character is inseparable from lysogenicity.

CULTIVATION OF LEPTOSPIRAE. II. GROWTH AND LYSIS IN SYNTHETIC MEDIUM

Stalheim, O. H. V. (University of Wisconsin, Madison), and J. B. Wilson. Cultivation of leptospirae. II. Growth and lysis in synthetic medium. J. Bacteriol. 88:55-59. 1964.-Differences were found in the ability of leptospirae to grow in a synthetic medium; 43 strains, consisting of 16 serotypes, were tested and designated as either type I or type II. Type I leptospirae did not grow; type II grew and could be subcultured. The lytic effect of several lipids was measured with Leptospira pomona and L. canicola as representatives of type I and II leptospirae, respectively. L. pomona organisms were rapidly lysed by the monoolein of the synthetic medium and by other lipids as well; L. canicola cells were consistently more resistant. Although both organisms incorporated similar amounts of label when incubated in the presence of oleic-1-C(14) acid, only L. canicola grew in a modified, nonlytic synthetic medium. No differences were found in susceptibility to lysis between virulent and avirulent L. canicola organisms. Mutant type I leptospirae grown in synthetic medium had increased resistance to lysis by surface-active agents; they were poorly agglutinated by antiserum. The role of protein in the growth and antigenicity of type I leptospirae is discussed.

SURVEY OF THE BACTERIOCINES OF ENTEROCOCCI

Brock, Thomas D. (Indiana University, Bloomington), Barbara Peacher, and Deborah Pierson. A survey of the bacteriocines of enterococci. J. Bacteriol. 86:702-707. 1963.-A survey has been made of bacteriocine production by a wide variety of well-characterized strains of group D streptococci. On the basis of spectrums and sensitivity to chloroform, heat, and proteolytic enzymes, five distinct bacteriocines can be defined. Type 1 is produced by all Streptococcus zymogenes (S. faecalis var. zymogenes) strains, is active against a wide variety of gram-positive bacteria, and is also a hemolysin. Type 2 is produced by some S. liquefaciens (S. faecalis var. liquefaciens) strains, and acts on many enterococci as well as on certain other lactic acid bacteria. Type 3 is produced by certain strains of both S. faecalis and S. faecium, and inhibits a wide variety of group D streptococci, but is inactive against all other lactic acid bacteria tested except Leuconostoc citrovorum. Type 4 is produced by certain S. faecium strains and resembles in certain ways the type 3 activity, but differs from it in other ways. Type 5 has been found to be produced by only one proteolytic strain of S. zymogenes, and this bacteriocine has a very narrow spectrum. The strain that produces this bacteriocine also produces type 1 activity. No strain is sensitive to a bacteriocine of the type it produces.

THE LYSIS OF CELL WALLS OF GROUP A STREPTOCOCCI BY STREPTOMYCES ALBUS ENZYME TREATED WITH DIISOPROPYL FLUOROPHOSPHATE. CHARACTERISTICS OF THE LYTIC REACTION AND THE SOLUBLE CELL WALL FRAGMENTS

Diisopropyl fluorophosphate (DFP) effectively inhibited proteolytic activity in preparations of partially purified Streptomyces albus enzyme used to lyse cell walls of Group A streptococci. Lysis of non-trypsinized Group A cell walls with DFP-treated S. albus enzyme released a soluble protein fraction containing antigenic type-specific M protein, a carbohydrate fraction consisting of Group A and a small amount of A-variant polysaccharides, and a dialyzable fraction. The similarities of the products of DFP-treated S. albus enzyme lysis of streptococcal cell walls to those released by phage muralytic enzyme furnish additional evidence of the close relationship of these wall lysins. In view of small differences in electrophoretic mobility, immunodiffusion, and chemical composition, it is suggested that Group A streptococcal cell wall polysaccharide dissolved by DFP-S. albus enzyme consists of a spectrum of molecules having the same immunological determinants but differing in content of conjugated mucopeptide.

CELL-WALL COMPOSITION AND OSMOTIC FRAGILITY OF SELECTED MARINE BACTERIA

Sud, I. J. (University of Florida, Gainesville), and M. E. Tyler. Cell-wall composition and osmotic fragility of selected marine bacteria. J. Bacteriol. 87:696-700. 1964.-Cell-wall composition of three marine pseudomonads, selected to represent a spectrum of osmotic fragilities, was determined and compared with that of Pseudomonas aeruginosa. The walls of the marine bacteria were composed predominantly of lipoprotein. No sugars, except glucosamine, were detected, and the reducing values were similar to the respective hexosamine values. These varied from 0.9 to 1.8%, the most osmotically fragile marine bacterium possessing the lowest amount of hexosamine in the wall. Possible relationship between wall hexosamine content and osmotic fragility was indicated.

STABILIZATION OF STREPTOCOCCUS FAECALIS PROTOPLASTS BY SPERMINE

Harold, F. M. (National Jewish Hospital, Denver, Colo.). Stabilization of Streptococcus faecalis protoplasts by spermine. J. Bacteriol. 88:1416-1420. 1964.-Lysis of protoplasts of Streptococcus faecalis subjected to osmotic shock was prevented by the presence of 10(-3)m spermine and other divalent cations. Protein and nucleic acids were largely retained, but compounds of low molecular weight were discharged into the medium and the capacity for glycolysis was lost. Under these conditions, spermine was bound to the protoplasts. It could not be removed by washing with water or nonelectrolytes, but was displaced by salts, polyanions, and polycations. Removal of the spermine restored the osmotic fragility of the protoplasts, which could once again be protected from lysis by impermeant solutes. Protoplasts were also stabilized, in the absence of osmotic shock, by prolonged incubation with cations in 0.5 m sucrose. By either procedure, the protoplasts became resistant not only to osmotic lysis but also to sonic oscillation. It is concluded that the stabilization of protoplasts resulted from ionic binding of the cation to acidic sites on the external surface of the plasma membrane. This conferred upon the membrane additional mechanical strength, perhaps by the cross-linking of subunits, but did not alter its permeability to extracellular solutes.

DISTRIBUTION OF RADIOACTIVITY IN AUTOLYZED CELL WALL OF BACILLUS CEREUS DURING SPHEROPLAST FORMATION

Kronish, Donald P. (Warner-Lambert Research Institute, Morris Plains, N.J.), Raam R. Mohan, and Benjamin S. Schwartz. Distribution of radioactivity in autolyzed cell wall of Bacillus cereus during spheroplast formation. J. Bacteriol. 87:581-587. 1964.-Spheroplasts of Bacillus cereus strain T were produced from cells grown in the presence of uniformly labeled C(14)-glucose. At regular intervals during spheroplast formation, enzymatically degraded cell wall was isolated by a new procedure. Radioactivity of solubilized cell wall in cell-free material increased from 2.5 to 42% of the total incorporated label during spheroplast formation. The rate of cell-wall degradation as measured by increase in radioactivity was biphasic with relative slopes of 2.0 and 5.0. During autolytic depolymerization of B. cereus cell wall, two major components were solubilized at different rates. Chemical fractionation revealed these to be a peptide and a mucopeptide. The possibility of two enzymes being involved in spheroplast formation and cell-wall degradation is discussed.

IMMUNOLOGIC STUDIES OF GLYCINE-INDUCED SPHEROPLASTS OF SALMONELLA TYPHI

The serological activity of glycine-induced spheroplasts and normal intact cells of Salmonella typhi was assessed. No major differences could be detected in the somatic O and in the Vi antigens of spheroplasts and intact cells. The only major change associated with transformation of normal typhoid organisms into spheroplasts seems to be associated with the flagellar antigen. Spheroplasts evoked a high H agglutinin response in immunized rabbits but were poorly agglutinated by standard H antiserum.The immunogenic ability of the spheroplasts to protect mice from the typhoid challenge was about five times higher than that of intact cells and the toxicity was reduced at least 10-fold.

SPONTANEOUS LYSIS AND PHAGE-CARRIER STATE IN BRUCELLA CULTURES

Renoux, Gerard (Université de Montpellier, Montpellier, France), and Andree Suire. Spontaneous lysis and phage-carrier state in Brucella cultures. J. Bacteriol. 86:642-647. 1963.-When broth or saline suspensions of 60 randomly chosen Brucella strains were directly poured onto plates of Albimi Agar, distinct plaques, indicative of phage activity, developed. Unselected Brucella cultures containing cell types that gave rise to several morphologically distinct colonial types all proved to be naturally phage-infected. Selection and study of some of these colonial types led to the following conclusions: (i) S or SI colonies do not carry the phage and are sensitive to it; (ii) pure R colonies are phage-resistant and do not carry the phage; (iii) butyrous or sticky white P ("Porteuses") colonies develop from "carrier cells" resistant to phage; and (iv) the progeny of cells of the P colony type segregate into cells that give rise to P, S, or SI colonies. However, when plates were streaked with a cotton swab soaked in the Brucella suspension, no visible plaque developed. The phenotypic changes occurring after phage infection are believed to play a role also under natural conditions; they are able to explain most of the natural behavior of Brucella. Their occurrence, however, does not exclude other genetic mechanisms that may produce similar phenotypic effects.

MUTANT OF LAMBDA BACTERIOPHAGE PRODUCING A THERMOLABILE ENDOLYSIN

Campbell, Allan (University of Rochester, Rochester, N.Y.) and Alice del Campillo-Campbell. Mutant of lambda bacteriophage producing a thermolabile endolysin. J. Bacteriol. 85:1202-1207. 1963.-Endolysin from lambda bacteriophage and a temperature-sensitive mutant thereof was partially purified. The mutant enzyme was distinguishable from the wild type by its greater rate of inactivation by high temperature and by urea. Lysogenic cells carrying the mutant phage did not lyse after induction if kept at 43 C, but, at times around 70 min after induction, rapid lysis occurred following transfer to lower temperatures. This lysis was not inhibited by cyanide or chloramphenicol and therefore probably resulted from enzyme already synthesized at the high temperature. Addition of these inhibitors to the culture at 43 C rapidly destroyed the ability to lyse after a subsequent temperature shift.

EFFECT OF CHOLESTEROL ON THE SENSITIVITY OF MYCOPLASMA LAIDLAWII TO THE POLYENE ANTIBIOTIC FILIPIN

Weber, Morton M. (St. Louis University School of Medicine, St. Louis, Mo.), and Stephen C. Kinsky. Effect of cholesterol on the sensitivity of Mycoplasma laidlawii to the polyene antibiotic filipin. J. Bacteriol. 89:306-312. 1965.-The polyene antibiotic, filipin, inhibited growth and caused lysis of Mycoplasma laidlawii cells which had been cultured in the presence of cholesterol. The antibiotic did not inhibit growth and did not promote lysis of the organism when grown in the absence of cholesterol. These results constitute strong support for the contention that the presence of sterol in the cell membrane is a necessary prerequisite for polyene sensitivity. Higher concentrations of filipin were required to inhibit growth when serum was added to the assay medium than when it was absent. These results suggest binding of the antibiotic to some component in the serum and may partially account for the previous inability to demonstrate growth inhibition by low concentrations of the polyene antibiotics. The extent of growth inhibition due to filipin decreased upon prolonged incubation. Subculture in the presence of high concentrations of antibiotic indicated that the apparent reversal of inhibition was caused by emergence of a filipin-resistant cell population. It was also observed that cells, which originally were rapidly lysed by filipin and digitonin, were no longer responsive to the action of these agents upon incubation in sterol-free medium at 25 or 37 C for several hours. This effect could be prevented by keeping the cells at 2 C. These results may indicate that filipin-resistant cells carry out a metabolic conversion of membrane-localized sterol to a form which can no longer react with the antibiotic. Other possible causes of resistance, which cannot be excluded on the basis of the present data, are discussed.

BINDING OF RIBOSOMES TO CYTOPLASMIC RETICULUM OF BACILLUS MEGATERIUM

Schlessinger, David (Washington University School of Medicine, St. Louis, Mo.), Vincent T. Marchesi, and Benjamin C. K. Kwan. Binding of ribosomes to cytoplasmic reticulum of Bacillus megaterium. J. Bacteriol. 90:456-466. 1965.-As many as 60% of the cellular ribosomes are bound to membrane "ghosts" in lysozyme lysates in 0.02 m Mg(2+). Bound ribosomes labeled with C(14)-uracil do not exchange with added unlabeled ribosomes, even after disruption of the cell membrane by sonic treatment. Electron micrographs of thin sections of ghosts, or of fragments produced by sonic disruption of protoplasts, indicate that the ribosomes are distributed on a reticular matrix which extends throughout the cytoplasm. The binding of ribosomes to this matrix is insensitive to ribonuclease or deoxyribonuclease, and has many other features in common with the binding of ribonucleoprotein to the membranous elements of the mammalian microsomal fraction, though the reticulum does not appear to be membranous. Thus, functioning ribosomes may be bound to a cytoplasmic structure in all cell types.

ISOLATION AND CHARACTERIZATION OF BACTERIOPHAGES ACTIVE ON CLOSTRIDIUM SPOROGENES

Betz, John V. (St. Bonaventure University, St. Bonaventure, N.Y.), and Kenneth E. Anderson. Isolation and characterization of bacteriophages active on Clostridium sporogenes. J. Bacteriol. 87:408-415. 1964.-Twelve bacteriophages active on the anaerobic species Clostridium sporogenes were studied. Four of these were isolated by the authors, and eight were obtained from L. S. McClung of Indiana University. The 12 phages studied could be distinguished into three groups on the basis of their plaque morphology, host range, receptor sites, and serological relationships. One group contained ten of the phages which were serologically related. These were separated into three subgroups on the basis of plaque morphology, host range, and receptor sites. The heat sensitivities of four phages were correlated with their classification in this scheme. Of 25 strains of C. sporogenes tested for lysogenicity, none was found to be lysogenic, but 9 produced bacteriocin-like substances and 20 were sensitive to one or more of these.

QUANTITATIVE STUDY OF ENDOLYSIN SYNTHESIS DURING REPRODUCTION OF LAMBDA PHAGES

Groman, Neal B. (University of Washington, Seattle) and Grace Suzuki. Quantitative study of endolysin synthesis during reproduction of lambda phages. J. Bacteriol. 86:187-194. 1963.-Endolysin is presumed to be a phage-induced enzyme participating in lysis through its destructive action on the host cell wall. A method for assaying endolysin is described, which was utilized in studying endolysin synthesis at 37 and 44 C by induced strains of K-12 (lambda), K-12 (lambdatem), and K-12 (lambda112). In all cases, endolysin was detected prior to the appearance of mature, intracellular phage and was detected earlier at 44 C than at 37 C. It was synthesized at a linear rate, as was phage, and both syntheses terminated at the same time. Surprisingly, endolysin also accumulated under conditions in which induced K-12 (lambda112) exhibited lysis inhibition. Under these conditions, endolysin concentration per induced cell was 2 to 2.5 times that produced by normally lysing K-12 (lambda). Since alterations introduced into the lytic process by temperature, mutation, or both correlate well with the timing and rate of endolysin synthesis, the data tend to support the concept that endolysin determines the kinetics of the process. However, the accumulation of endolysin during lysis inhibition suggests the need for alternative hypotheses. One hypothesis is that although endolysin action is the key to lysis some preliminary steps are required to release the enzyme so that it may contact its substrate in the cell wall. A second hypothesis is that basically the lytic process involves an alteration in the permeability barrier of the cell and that lytic enzymes such as endolysin have evolved as an auxillary but dispensable mechanism to this process.

OBSERVATIONS ON THE GROUP C STREPTOCOCCAL BACTERIOPHAGE AND LYTIC ENZYME SYSTEM

Fox, Eugene N. (La Rabida-University of Chicago Institute, Chicago, Ill.), and Masako K. Wittner. Observations on the group C streptococcal bacteriophage and lytic enzyme system. J. Bacteriol. 89:496-502. 1965.-The phage-associated lytic enzyme of group C streptococci was assayed by measuring the solubilized portion of radioactive cell walls. By this sensitive assay system, the induced synthesis of the lytic enzyme was observed intracellularly during phage infection; at least half of the total enzyme was synthesized and remained intracellular during the eclipse period, and was then released with the liberation of mature phage. Lytic enzyme could be detected in only two of eight lysogenic strains during temperate-phage production after ultraviolet induction. Virulent phage purified by density-gradient centrifugation contained lytic enzyme presumably associated with the virus per se. No hyalyronidase was detected in association with the phage, nor was this enzyme induced during phage synthesis. Variant strains of group C streptococci, no longer serologically active, were isolated as phage-resistant mutants. These strains still adsorbed the phage, but without subsequent virus reproduction, indicating that the group polysaccharide was not the primary receptor for the virus.