[Use of an experimental analytical method for equilibrating nutrient broths for Clostridium perfringens type A growth and toxin formation]. / Ispol'zovanie éksperimental'no-analiticheskogo metoda dlia balansirovki zhidkikh pitatel'nykh sred dlia rosta i toksinoobrazovaniia Clostridium perfringens tipa A.

A successful attempt to use analytico-experimental approach to the evaluation of experimental data for the scientifically based calculation of the composition of complex culture media, intended for growing pathogenic microorganisms, has been made. The method is based on the evaluation of the specific growth-stimulating and toxin-forming activity of the components of a given culture medium, which are determined by the number of cells grown in the variants of the medium with the limited amount of one of its components. The use of the analytico-experimental balancing method makes it possible to develop culture media with the optimal composition ensuring the definite yield of the target product rather quickly and economically by experimenting on the minimal number of variants equal to the number of the components of the medium. The investigation carried out by means of the analytico-experimental method has revealed that on the basis of peptic serum albumin hydrolysate, pancreatic casein hydrolysate and fodder yeast extract, alongside the culture medium described in an earlier work and containing these components in the proportion 4:2:1, two other media, containing the above components in the proportion 2:4:1 and 3:4:2, can be obtained, these media providing the optimal conditions for, respectively, the toxin formation and growth of C. perfringens, type A.

[Effect of iron on the growth and toxin formation of Clostridium perfringens type A cultures]. / Izuchenie vliianiia zheleza na rost i toksinoobrazovanie kul'tur Clostridium perfringens tipa A.

The influence of iron at different concentrations on the growth and toxin formation of the cultures of C. perfringens strain 28 BP6K, type A, in media having different composition and protein base has been studied. As revealed by the results of these studies, bivalent iron at concentrations of 1-30 mg%, while having no essential influence on the growth and development of the culture, not only produces no stimulating effect on toxin formation, but even inhibits it. The concentrations of iron, both producing the optimum effect on toxin formation and inhibiting it, are not identical for different kinds of culture media and depend on their nature and composition. In culture media with fodder yeast extract added, and especially in media based on fermentative fodder yeast hydrolysate, the cultures have shown the increased stability of toxin formation in the presence of higher concentrations of iron.

[Antigenic fractions of Clostridium oedematiens toxin and their immunogenic properties]. / Antigennye fraktsii toksina Clostridium oedematiens i ikh immunogennye svoistva.

The results of the isolation of antigenic fractions and their complexes from Cl. oedematiens toxin and the study of their antigenic properties are presented. The purified, concentrated toxin has been found to consist of high- and low-molecular antigens differing in immunogenicity and affinity to aluminium hydroxide used as sorbent. Preparations obtained from low-molecular antigens easily adsorbed by the low doses of the sorbent possessed high specific and immunogenic activity.

[Comparative study of the physico-chemical properties of peptones used to the production of dry alkaline agar for cholera diagnosis]. / Sravnitel'noe izuchenie fiziko-khimicheskikh svoistv peptonov, ispol'zuemykh v proizvodstve sukhogo shchelochnogo agara dlia diagnostiki kholery

The authors present the results of chemical and physico-chemical study of dry peptones (made in the USSR) used in the production of dry alkaline nutrient agar for the diagnosis of cholera, in comparison with peptones used for other purposes. The batches and types of peptones studied differed by the fractional peptide composition and by the physico-chemical characteristics. Positive results were obtained in the biological test in using peptones with marked hydrolysis with the amine nitrogen content of not less than 200--230 mg%, with an elution curve approaching the Hottinger's peptone curve, well soluble in buffer phosphate solution at 5% concentration.