and so that under T the sign of the coordinate x, remains invariant. LEMMA 5.1. The mapping k = s t-1 I is a C'-diff. of E P onto X*. 6. Solution of a Problem of Type K.-Let D be an n-interval in E, geometrically similar to H', containing P, and with the vertex (a) in common with H' (ai = -1; i = 1, .. ., n). Let Di D 0' be a second n-interval, geometrically similar to H' and D, with vertex (a), and with H' D Di. Note that D v Di. We define a C'-diff. a of D onto H', which leaves Di pointwise invariant. The open subsets

https://www.pnas.org/content/pnas/44/10/1072.full.pdf

Transformation of biochemically deficient strains of bacillus subtilis by deoxyribonucleate

Infective heredity of multiple drug resistance in bacteria

INTRODUCTION ........................................................ 291 General ............... ......................................... 291 Cell Waill Structure and Synthesis ....................... ........................ 292 Identification of the Target of Penicillin Action .......... ........................ 293 PENICILLIN-BINDING COMPONENTS .............. .......................... 296 What Is Actually Bound? ....................................................... 298 How Much Penicillin Do Cells Bind? ................. ........................... 298 Is the Penicillin Bound Covalently? ................... .......................... 299 To What Group Does PenicillinBind?..... 299 Under What Conditions Can Penicillin Be Released from the PBCs?........ ........ 300 What Is the Physical Nature ofthe PBCs? ............. .......................... 300 Are PBCs Located in Peripheral Membranes, Mesosomes, or Both? ...... ........ 301 Do Organisms Have One or Multiple Proteins Which Bind Penicillin? ..... ...... 301 Isolation ofPBCs by Covalent Affinity Chromatography ........ ................. 303 What Is the Relationship of the PBCs to the Killing Site? ....... ................. 304 Biochemical Evidence for the Involvement ofPBCs in Peptidoglycan Synthesis . . 305 PENICILLIN-SENSITIVE ENZYMES ................ ........................... 306 Transpeptidase......................................................... 306 Transpeptidase assayed with natural acceptor in a coupled system ............ 306 Transpeptidase assayed with unnatural acceptor in a coupled system ..... ..... 307 Transpeptidase assayed in a simple, uncoupled system ....... ................. 307 D-Alanine Carboxypeptidase .................................................... 308 E. coli carboxypeptidase ...................................................... 309 Carboxypeptidases from Bacillus ................... .......................... 309 Streptomyces carboxypeptidases .................... .......................... 309 Endopeptidase......................................................... 313 Other Activities ........................................................ 314 Number of Enzymes Corresponding to the Different Penicillin-Sensitive Enzymatic Activities ........................................................ 314 Relationship ofthe Penicillin-Sensitive Enzymes to the PBCs ....... ............. 316 Physiological Functions ofthe Penicillin-Sensitive Enzymes ....... .............. 316 Physiological Evidence for the Existence of Multiple Transpeptidases ..... ...... 318 Kinetics of Penicillin Inhibition ................................................. 319 Models for the Interaction ofPenicillin with Its Target ........ .................. 321 MECHANISM OF KILLING BY PENICILLINS .......... ....................... 324 Mutant Analysis........................................................ 324 Evidence That Penicillin Kills by Inhibiting Cross-Linking ...................... 324 Killing by Amidino Penicillin ................................................... 325 Transfer of Penicillin Side Chain ................................................. 325 CONTROL OF CELL WALL SYNTHESIS ............. .......................... 326 SUMMARY ................ ....................................... 327 LITERATURE CITED ....................................................... 327

Interaction of penicillin with the bacterial cell: penicillin-binding proteins and penicillin-sensitive enzymes.

Spheroplast production by lysozyme and ethylenediaminetetraacetate (EDTA) was examined as a means of obtaining osmotically sensitive cells for studies of enzyme localization. Physiologically young cells plasmolyzed with 0.5 m sucrose in 0.01 m tris(hydroxymethyl)aminomethane (Tris) buffer (pH 7, 8, or 9) were quantitatively converted to plasmolyzed osmotically sensitive rods after lysozyme treatment. Although such cells were osmotically sensitive, a 1:1 dilution in Tris buffer was necessary for conversion of rods into spheroplasts. Addition of EDTA resulted in a rapid conversion of the plasmolyzed spheroplasts into spherical structures devoid of a plasmolysis vacuole. These structures, which we call EDTA-lysozyme spheroplasts, contained a number of attached membranes. We believe that this conversion results from a weakening of the outer trilaminar component of the cell wall by EDTA, resulting in the collapse of the plasmolysis vacuole. Dilution of sucrose below 0.15 m also resulted in the collapse of the plasmolysis vacuole. Both the lysozyme spheroplasts and the EDTA-lysozyme spheroplasts were osmotically sensitive. Thin sections of the EDTA-lysozyme spheroplasts demonstrated that the outer trilaminar component of the cell wall was broken, exposing large areas of the cytoplasmic membrane to the environment.

Production and Ultrastructure of Lysozyme and Ethylenediaminetetraacetate-Lysozyme Spheroplasts of Escherichia coli

Certain improvements are described in the use of penicillin for isolating auxotrophic mutants of bacteria. By obtaining exponential growth before the penicillin is added, and by minimizing the duration of the treatment, cross-feeding is decreased and much denser populations can be screened. These modifications have made it possible to obtain, with regularity, mutants of Escherichia coli blocked in a desired step in arginine biosynthesis.

http://science.sciencemag.org/content/sci/131/3400/604.full.pdf

Selecting Bacterial Mutants by the Penicillin Method

A preceding article (Lederberg, 1956a) was devoted to the evolution of protoplasts from growing cells of Escherichia coli treated with penicillin. Further studies have strengthened the correspondence of these protoplasts with the \"large bodies\" and \"L forms\" described for many other bacteria. This paper will give an account of these studies, and an interpretation of others, in support of the hypothesis that L forms are outgrowths of protoplasts. Their cell walls may be impaired either by extrinsic inhibition, for example, with penicillin, or by intrinsic metabolic defects, consequences of genetic mutations. The previous study was motivated mainly by the hope of furnishing protoplasts of genetically defined strains of E. coli for physiological and genetic analysis (Spiegelman, 1956; Spooner and Stocker, 1956). It was modeled on the experiments of Weibull (1953a) who forestalled the lysis of Bacillus megaterium exposed to lysozyme by maintaining the bacteria in a protective, hypertonic medium. It was found that the lysis of growing E. coli in the presence of penicillin could be forestalled in a medium containing M/3 sucrose and M/100 Mg; instead of lysing, the rods burgeoned out into osmotically fragile spheres, considered to be protoplasts. Similar effects of penicillin on growing bacteria have been described extensively from an altogether different viewpoint as an aspect of the development of L forms. For various reasons, species other than E. coli have been preferred for such studies. In general, the wall defects have been recognized but not stressed as the essential feature of L forms, and their relationship to protoplasts obtained with lysozyme has been

Protoplasts and L-type growth of Escherichia coli.

Phage host range is a useful marker in epidemiological and genetic studies of phages. Conversely, phages can often discriminate among organisms not separable serologically, thus constituting the basis of phage typing. Plaque morphology may provide identification of both host and phage still more precisely than host range or phage sensitivity. For purposes of such identification it would be valuable to know if some characteristics of plaques are controlled by the phage and others by the host. In the following survey, a number of freshly isolated phages were plated with several Streptomyces species and morphology of their plaques observed with the above question in mind.

Plaque morphology of certain streptomycete phages.

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Protoplasts and L-type growth of Escherichia coli.

Plaque morphology of certain streptomycete phages.