UNSTABLE LINKAGE BETWEEN GENETIC MARKERS IN TRANSFORMATION

Kelly, M. (Hammersmith Hospital, London, England), and R. H. Pritchard. Unstable linkage between genetic markers in transformation. J. Bacteriol. 89:1314-1321. 1965.-A new type of association of genetic markers in a transformation system has been discovered. Linkage between certain markers is detectable only under particular conditions of deoxyribonucleic acid (DNA) extraction and is sensitive to dilution of the DNA. The data suggest that this unstable association occurs between markers which are on the same molecule but separated by a molecular distance sufficiently great for linkage to be preserved only by mild DNA extraction procedures and at high concentrations of DNA. Linkage can be stabilized by dilution in the presence of a carrier DNA. By use of these unstable linkages, the genetic map of Bacillus subtilis has been extended in both directions from the aromatic gene cluster.

RADIOSENSITIVITY OF SEVERAL DEHYDROGENASES AND TRANSAMINASES DURING SPOROGENESIS OF BACILLUS SUBTILIS

Rowley, D. B. (Syracuse University, Syracuse, N.Y.), and H. R. Newcomb. Radiosensitivity of several dehydrogenases and transaminases during sporogenesis of Bacillus subtilis. J. Bacteriol. 87:701-709. 1964.-Cells of Bacillus subtilis grown in a chemically defined medium for 17 hr, subsequently washed, and transferred to a phosphate solution containing CaCl(2) sporulated in a reproducible pattern. The synthesis of dipicolinic acid essentially paralleled the appearance of thermoresistant cells. X-ray resistant cells appeared 2 to 3 hr before the appearance of thermoresistant cells and the formation of dipicolinic acid. Changes in enzyme activity of cells undergoing sporogenesis varied among the enzymes studied. The transaminases exhibited a marked decrease in activity during early sporogenesis, whereas the dehydrogenases exhibited maximal activity. The determination of enzyme radioresistance in extracts of sporulating cells indicated that the resistance of transaminases remained essentially unchanged, whereas the dehydrogenases exhibited a decreased resistance early in sporogenesis. Although both glutamic-pyruvic transaminase and glutamic-oxaloacetic transaminase (GOT) were demonstrated in vegetative cells, only the latter was detected in mature spores. The radioresistance of GOT in vegetative-cell extracts was two to three times greater than in spore extracts.

SEROLOGY OF THE SOLUBLE ANTIGENS OF THE PATHOGENIC CLOSTRIDIA

Ellner, Paul D. (University of Vermont, Burlington), and Stanley S. Green. Serology of the soluble antigens of the pathogenic clostridia. J. Bacteriol. 86:1084-1097. 1963.-Soluble antigens of 42 strains, representing nine species of clostridia commonly occurring in human infections, were prepared by growing the organisms in a nonantigenic medium. Serological studies demonstrated the occurrence of considerable strain variation within each species. Interactions among the nine species, as well as with the previously characterized Clostridium perfringens, were also investigated. Extreme heterogeneity was observed among the species studied, with many cross-reactions due to common antigens, although species-specific antigens were also found in some cases. Occasional weak reactions were also demonstrated between certain clostridial antisera and the soluble antigens of three of the four species of Bacillus studied.

EFFECT OF PHENOL ON BACILLUS SUBTILIS SPORES AT ELEVATED TEMPERATURES

The nature of the recovery medium is shown to influence the number of Bacillus subtilis spores which, after exposure to 2.5 or 5% phenol at high temperatures, can produce a visible colony. Higher survivor counts were obtained in nutrient agar containing L-alanine and D-glucose than in plain nutrient agar.

FURTHER STUDIES ON THE REGULATION OF AMINO SUGAR METABOLISM IN BACILLUS SUBTILIS

1. Glucosamine 6-phosphate deaminase [2-amino-2-deoxy-d-glucose 6-phosphate ketol-isomerase (deaminating), EC 5.3.1.10] of Bacillus subtilis has been partially purified. Its K(m) is 3.0mm. 2. Extracts of B. subtilis contain N-acetylglucosamine 6-phosphate deacetylase (K(m) 1.4mm), glucosamine 1-phosphate acetylase and amino sugar kinases (EC 2.7.1.8 and 2.7.1.9). 3. Glucosamine 6-phosphate synthetase (l-glutamine-d-fructose 6-phosphate aminotransferase, EC 2.6.1.16) is repressed by growth of B. subtilis in the presence of glucosamine, N-acetylglucosamine, N-propionylglucosamine or N-formylglucosamine. Glucosamine 6-phosphate deaminase and N-acetylglucosamine 6-phosphate deacetylase are induced by N-acetylglucosamine. Amino sugar kinases are induced by glucose, glucosamine and N-acetylglucosamine. The synthesis of glucosamine 1-phosphate acetylase is unaffected by amino sugars. 4. Glucose in the growth medium prevents the induction of glucosamine 6-phosphate deaminase and of N-acetylglucosamine 6-phosphate deacetylase caused by N-acetylglucosamine; glucose also alleviates the repression of glucosamine 6-phosphate synthetase caused by amino sugars. 5. Glucosamine 6-phosphate deaminase increases in bacteria incubated beyond the exponential phase of growth. This increase is prevented by glucose.

CONFIGURATION OF TRANSFORMING DEOXYRIBONUCLEIC ACID DURING ENTRY INTO BACILLUS SUBTILIS

Strauss, Norman (Yale University, New Haven, Conn.). Configuration of transforming deoxyribonucleic acid during entry into Bacillus subtilis. J. Bacteriol. 89:288-293. 1965.-A correlation was obtained between map distance and the length of the lag period preceding the appearance of pairs of genetic traits after the addition of deoxyribonucleic acid (DNA) to a competent culture of Bacillus subtilis. The results are taken to indicate that DNA enters competent cells in lengthwise fashion. The smallest length of transforming DNA which can participate in a recombination event, and the number of nucleotide pairs which enter the cell per unit time, have been estimated. The evidence indicates that only part of the lag period is devoted to the transport of DNA into the cell. The significance of these results with respect to the mechanism of entry of DNA into the cell is discussed.

PRODUCTION AND PARTIAL PURIFICATION OF ANTIBIOTIC MATERIALS FORMED BY PHYSARUM GYROSUM

Pure cultures of Physarum gyrosum were grown on agar plates with autoclaved Escherichia coli suspensions as the growth medium. Portions of such agar, after growth of the slime mold, contained diffusible materials that inhibited the growth of Bacillus subtilis, B. cereus, E. coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Paper chromatography of extracts of such cultures revealed at least three different active fractions. Preliminary fractionations increased the specific activity by one order of magnitude, probably in part by removal of inactive material and in part by separating active components. The fractionations also demonstrated the multiplicity of the antibiotic activity. Fractions variously obtained always retarded the growth of the bacterial species listed above.

A CYTOCHEMICAL LOCALIZATION OF REDUCTIVE SITES IN A GRAM-POSITIVE BACTERIUM. TELLURITE REDUCTION IN BACILLUS SUBTILIS

In bacteria the exact location of a respiratory enzyme system comparable to that of the mitochondria of other cells has remained uncertain. On the one hand, the existence of particulate "bacterial mitochondria" has been advocated (Mudd); on the other hand, important enzymes of the respiratory chain were recovered in the cytoplasmic membranes associated with some granular material (Weibull). In order to gain insight into this question, sites of reducing activity were localized in thin sections of bacteria using the reduction of potassium tellurite as an indicator. When this salt was added to the culture medium of Bacillus subtilis, it turned out that in this Gram-positive organism the reduced product is strictly bound at two sites, and that the plasma membrane does not materially gain in electron opacity through deposition of the reduced product. The reduction product is found on or in the membranes of particular organelles, which may possibly be regarded as the mitochondrial equivalents in Gram-positive bacteria, and which are sometimes seen connected to the plasma membrane. The second location is in thin rod-like elements at the cell periphery, possibly the sites from which the flagella emerge.