ELECTRON MICROSCOPE STUDY OF THE RELATIONSHIP BETWEEN MESOSOME LOSS AND THE STABLE L STATE (OR PROTOPLAST STATE) IN BACILLUS SUBTILIS

Ryter, Antoinette (Institut Pasteur, Paris, France), and Otto E. Landman. An electron microscope study of the relationship between mesosome loss and the stable L-state (or protoplast state) in Bacillus subtilis. J. Bacteriol. 88:457-467. 1964.-In a prior publication, it was postulated that inability of protoplasts to restart cell-wall synthesis and cell division and the inability of stable mass-conversion L forms to return to the bacillary state were both equivalent and both due to the interruption of a membrane-associated reaction sequence. It was further postulated that this reaction sequence might reside in the mesosome. In the present publication, it is shown by means of electron microscopy of thin sections that protoplasts and L forms do not contain mesosomes. The sequence of events leading to loss of the mesosomes during protoplasting is as follows. Soon after lysozyme addition, the mesosomes are extruded from the cell interior into the space between cell wall and cytoplasmic membrane. Mesosome fragments in the form of small vesicles gather at the poles of the cells and are released, along with intact protoplasts, when the wall fragments. (Sudden shift of bacilli to hypertonic environment also causes extrusion and fragmentation of mesosomes, but this damage is later repaired.) In intact bacilli, mesosomes are in contact with both the peripheral membrane and nuclear material. Upon extrusion of the mesosomes, a direct attachment between nuclear material and cytoplasmic membrane is observed. Deoxyribonucleic acid (DNA)-membrane attachment may play a role in the control of DNA replication. Bacillus subtilis L-colonies consist of irregularly shaped bodies of varying sizes, bounded only by a membrane. Many of the smaller bodies do not contain nuclear material, and many of the large ones appear inviable. Division is accomplished by a disorganized-appearing constriction process. There are no septa.

X-RAY DIFFRACTION STUDY OF A DNA WHICH CONTAINS URACIL

Three-dimensional structure of DNA from PBS2 bacteriophage, which contains uracil in place of the more usual thymine, is the same as that of "normal" DNA. The difference in secondary structure between DNA and RNA thus appears to be due to the 2'-hydroxyl group alone.

MECHANISM OF RESISTANCE TO ACTINOMYCIN IN BACILLUS SUBTILIS

Polsinelli, M. (University of Pavia, Pavia, Italy), O. Ciferri, G. Cassani, and A. Albertini. Mechanism of resistance to actinomycin in Bacillus subtilis. J. Bacteriol. 88:1567-1572. 1964.-Strains of Bacillus subtilis were rendered resistant to actinomycin D by serial transfer in increasing concentrations of the drug. Resistance to the antibiotic appeared to be due to an altered cell-wall permeability, because the resistant strains did not take up actinomycin. No evidence was found for the presence of an enzyme(s) degrading actinomycin. Deoxyribonucleic acid (DNA) extracted from the actinomycin-resistant strains was found to bind actinomycin to the same extent as the DNA extracted from susceptible strains. The genetic nature of the resistance to actinomycin was demonstrated by means of transformation. Resistant strains appeared to have almost completely lost their transformability, as well as the tendency to autolyze.

INHIBITION OF BACTERIAL GROWTH BY DRUGS OF THE MORPHINE SERIES

The growth of Escherichia coli is reversibly inhibited by drugs of the morphine series. The order of inhibitory effectiveness for the drugs tested was levallorphan > levorphanol > dextrorphan > nalorphine > morphine. The synthetic analgesic, levorphanol, was studied in greater detail. Its effectiveness was found to be strongly dependent on the pH of the medium. Raising the pH of the medium provides a higher concentration of the neutral free base which is thought to diffuse across cell membranes more readily. However, considerations other than the rate of entry of drug into the cells must be of importance since an already established growth inhibition is promptly reversed upon lowering the pH of the medium. Two mutants of Escherichia coli with altered sensitivity to levorphanol were isolated.

ISOLATION OF OBLIGATELY ANAEROBIC PSYCHROPHILIC BACTERIA

Sinclair, N. A. (Washington State University, Pullman), and J. L. Stokes. Isolation of obligately anaerobic psychrophilic bacteria. J. Bacteriol. 87:562-565. 1964.-A total of 11 strains of strictly anaerobic psychrophilic bacteria have been isolated from soil, mud, and sewage. The organisms grow well at 0 C in liquid and on solid media, and grow only in the complete absence of oxygen. On the basis of shape, sporulation, flagellation, and strictly anaerobic growth, all of the organisms were classified as strains of Clostridium. Some of the biochemical properties of the strains and the effect of temperature on growth are described.

ACETOLACTATE METABOLISM AND THE PRESENCE OF A DIHYDROXY ACID DEHYDRATASE IN MICRO-ORGANISMS

1. The growth characteristics of nine micro-organisms on complex broth and defined media, usually with a single nitrogen source (other than vitamins), were examined as a necessary step before growth of cells for enzyme assays. Six of these bacteria gave a positive colour test with a creatine-potassium hydroxide reagent, indicating the presence of acetoin, which other investigators have shown is formed via the intermediate, alpha-acetolactate. 2. Cell-free extracts of exponential-phase cells of Bacillus subtilis, Staphylococcus aureus, Proteus morganii, Acetobacter rancens (two strains), A. kuetzingianus, A. acetosus, Acetomonas (Acetobacter) melanogenus and Acetomonas (Acetobacter) suboxydans (A.T.C.C. no. 621) were found to contain the enzyme, dihydroxy acid dehydratase (2,3-dihydroxy acid hydro-lyase). 3. The specific activity of the dehydratase from organisms grown on valine- and isoleucine-deficient media was greater than those grown on a complex broth or media containing complete amino acid mixtures. The omission of valine plus isoleucine from a medium containing 19 amino acids caused an increase in the dehydratase specific activity of Staphylococcus aureus and Proteus morganii. 4. The rate of keto acid formation from alphabeta-dihydroxyisovalerate by extracts of six of the above-named organisms was faster than, but somewhat proportional to, the similar rate from alphabeta-dihydroxy-beta-methyl-n-valerate as substrate. 5. These findings may be related to acetolactate synthesis, acetoin formation and valine-isoleucine biosynthesis in the above-mentioned micro-organisms.

UPTAKE AND INCORPORATION OF THYMINE, THYMIDINE, URACIL, URIDINE, AND 5-FLUOROURACIL INTO THE NUCLEIC ACIDS OF BACILLUS SUBTILIS

Bodmer, Walter F. (Stanford University School of Medicine, Palo Alto, Calif.), and Susan Grether. Uptake and incorporation of thymine, thymidine, uracil, uridine, and 5-fluorouracil into the nucleic acids of Bacillus subtilis. J. Bacteriol. 89:1011-1014. 1965.-From 55 to 95% of uracil, uridine, or 5-fluorouracil (FU) added to the culture medium is incorporated into the acid-insoluble fraction of cells of Bacillus subtilis strains SB 19 (prototroph) and SB 503 (FU-resistant). Thymine is poorly incorporated (less than 1%); thus, the incorporation of thymidine is limited (less than 12%) by the rapid degradation of the nucleoside to thymine, probably by the enzyme thymidine phosphorylase. Uracil, uridine, and FU were not incorporated into the deoxyribonucleic acid (DNA) of either strain, whereas all the incorporated thymidine was found in the DNA.

TRANSFORMATION OF BACILLUS SUBTILIS TO MOTILITY AND PROTOTROPHY: MICROMANIPULATIVE ISOLATION OF BACTERIA OF TRANSFORMED PHENOTYPE

Stocker, B. A. D. (Stanford Medical Center, Palo Alto, Calif.). Transformation of Bacillus subtilis to motility and prototrophy: micromanipulative isolation of bacteria of transformed phenotype. J. Bacteriol. 86:797-804. 1963.-A nonmotile (nonflagellated, fla(-)) try(-) strain of Bacillus subtilis was transformed to fla(+) and to try(+) by wild - type deoxyribonucleic acid (DNA) at comparable rates. Bacteria of fla(+) phenotype were recognized by their motility approximately 3 hr after uptake of DNA, and bacteria of try(+) phenotype at about the same time by their elongation into filaments in a medium lacking tryptophan. Of phenotypically transformed bacteria of each sort isolated by micromanipulation, the majority produced only transformed progeny, a mixture of transformed and untransformed, or a mixture of two kinds of transformant. Some produced only untransformed progeny, or progeny transformed only at a locus linked to that concerned in their phenotypic transformation. In a few clones, some partial heterozygotes were present even ten generations after DNA uptake. In nonmotile clones derived from motile isolates, the unilinear transmission of motility to one to four descendants was detected; it is attributed to persistence of a corresponding number of units of some product of an unincorporated fla(+) gene, probably flagella or cell walls each carrying several flagella. No pedigrees indicating unilinear transmission of an unincorporated fla(+) gene were observed.

SURVIVAL OF MICROORGANISMS IN A SIMULATED MARTIAN ENVIRONMENT. I. BACILLUS SUBTILIS VAR. GLOBIGII

Survival of Bacillus subtilis var. globigii in a simulated Martian environment was demonstrated. Previous contact with the simulated Martian soil or atmosphere reduced germination or outgrowth of unheated spores, or both. Inoculation into simulated Martian soil and then flushing with a simulated Martian atmosphere were lethal to both vegetative cells and spores. After one diurnal temperature cycle (26 to -60 C), the majority of of cells present were spores. No further effect of the diurnal cycle on survival was noted in any of the experimental samples.