Dehydrogenase activity and toxinogenesis of a production strain ofCorynebacterium diphtheriae during submerged cultivation

A simple biochemical procedure was obtained for studying metabolism ofCorynebacterium diphtheriae during submerged cultivation based on the modification of the assay of dehydrogenase activity using 2,3,5-triphenyltetrazolium chloride as redox indicator. Results obtained by the estimation of the dehydrogenase activity using TTC are in a good accordance with oxygen consumption assayed manometrically. By following dehydrogenase activity in submerged cultivations of a production strain ofCorynebacterium diphtheriae PW8-Weissensee we found that a massive toxin production is connected with the decrease of the activity of cells. This fall of activity occurs yet during the exponential phase of growth. Especially a sudden fall of succindehydrogenase activity exactly indicates the beginning of a considerable toxin accumulation in the medium. The presence of inhibitory concentrations of iron ions in the medium not only increases the level of dehydrogenase activity but changes its whole kinetics. A retarded and irregular fall of the activity occurs instead of a sharp one typical for good toxin production.     

The genusSaccharomyces (Meyen) Reess

The authors submit a taxonomic evaluation of an intermediate group of strains between the speciesSaccharomyces carlsbergensis Hansen andSaccharomyces cerevisiae Hansen. The material consisted of atypical strains of “bottom” brewer’s yeasts and the synonymous strainsSaccharomyces monacensis Hansen andSaccharomyces mandshuricus Saito. It was found that there were two different serological types in the speciesSaccharomyces carlsbergensis, one of which was characterized by the presence of antigen “C” and was typical for this species, while the other possessed antigen “M” and was grouped roundSaccharomyces monacensis. This second serological type merges with a group of strains which gives only one third fermentation of raffinose, so that it is actually an intermediate betweenSaccharomyces cerevisiae Hansen andSaccharomyces carlsbergensis Hansen and indicates the course of progressive development from the former species to the latter. No close similarity was found betweenSaccharomyces mandshuricus Saito and some of the strains of the transitional group or typical representatives of the two main species, and the authors therefore consider that there is some obscurity as to its synonymity withSaccharomyces carlsbergensis.     

Changes in the radioresistance of bacteria after the inhibition of proteosynthesis in the preirradiation phase

The strain ofEscherichia coli WP₂ (try_v) was irradiated with UV light, at a dosage of 240 erg/mm. Proteosynthesis was inhibited by the elimination of the essential amino acid from the cultivation medium. Changes in radioresistance were followed during 45 minutes of starvation and during the subsequent 45 minutes of restitution after the addition of the essential amino acid. The radioresistance of the cells showed a linear increase immediately after the removal of the essential amino acids, proportional to the duration of the inhibition of proteosynthesis. The increase in radioresistance was shown to be reversible. After the addition of the essential amino acid there was an immediate decrease in radioresistance which was most marked in the first 15 minutes.     

Occurrence of cytochromes in R and S yeast mutants of the genusSaccharomyces

Visible region of an absorption spectrum was followed in cells of original strains and of rough mutants ofSaccharomyces cerevisiae andS. cerevisiae var.ellipsoideus. It was found that there are no substantial differences in relative content of cytochromesb andc in aerobically grown rough and smooth yeast forms, in spite of the fact that both forms differ substantially in the metabolic oxygen quotient. If the cytochromes present were not reduced in washed cells by dithionite or by substrate addition, the rough forms exhibited a lower cytochrome b:c ratio than the smooth forms. Under anaerobic conditions of cultivation, the rough forms retained a typical aerobic spectrum, lacking, however, the cytochromea and a₃ band; the ratio of cytochromesb andc was changed in favour of cytochromeb (from the original 1.7: 1 up to 3.4: 1). The inability of the rough mutants to produce anaerobic cytochrome spectrum represented by cytochrome b₁ was connected with their inability to reproduce under anaerobic conditions.     

Phospholipidgranula im verhornenden Oesophagusepithel

Zusammenfassung Im Epithel des Meerschweinchenoesophagus fanden wir mit Ausnahme des Stratum corneum in jeder Schicht 0,1–0,3 große, lamellär-strukturierte Granula. Die Granula werden meistens von einer Membran (unit-membrane) umgeben, die ein lamelläres System in sich einschließt, das eine Periodizität von 60–70 Å aufweist und aus dunklen und hellen Lamellen besteht. Unsere Annahme, daß die Granula Phospholipide enthalten, wird durch die Beobachtung unterstützt, daß die Lokalisation der lichtmikroskopisch durchgeführten Baker-Reaktion vollkommen mit der Verteilung der lamellären Granula im elektronenmikroskopischen Bild übereinstimmt. Nach Pyridinextraktion ist die Baker-Reaktion negativ, während im elektronenmikroskopischen Material an Stelle der Granula nur Vakuolen zu finden sind.Die Granula erscheinen im Stratum germinativum meistens in Verbindung mit dem Golgiapparat und entleeren sich in Höhe des Stratum granulosum in den interzellulären Raum. Zwischen den Lamellen des Stratum corneum ist das Material der Granula als eine homogene, dunkle, amorphe Deckschicht vorhanden. Ihre Aufgabe besteht wahrscheinlich in der Steigerung der Resistenz der Hornschicht.

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Summary Lamellated granules of 0,1 to 0,3 in diameter are consistently found in all strata of the keratinizing epithelium of the guinea pig oesophagus. The granules are surrounded by a single membrane (unit membrane) and contain a lamellated system consisting of dark and light bands showing a periodicity of 60 to 70 Å. The supposed phospholipid nature of the granules was supported by the positive Baker-reaction at the light microscope level. The distribution of the Baker-positive substance was identical with that of the lamellated granules at the electron micrograph. After extraction with pyridin, the Baker-reaction turned out to be negative while on the electron micrographs the substance of the lamellated granules was lost.The granules first appear near the Golgi region of the stratum germinativum and are emptied into the extra-cellular space at the level of the stratum granulosum. The substance of the granules, after having lost their lamellated structure, remains between the keratinized layers as a homogenous, dense material. Its function probably consists in increasing the resistance of the cornified layer against chemical agents.