[Morphology of Streptomyces chrysomallus microcolonies in submerged cultivating].

Gel matrix covering microcolonies and individual hyfs and cords of mycelial hyfs was for the first type detected using a special method for making preparations for microscopic examinations. The matrix is observed during culturing streptomycetes in media of different composition for mycelium of different age. Gel matrix renders the colonies a compact shape and can be regarded as a specific structural component of Streptomyces microcolonies.

[The effect of heat shock on the formation and composition of actinomycins].

The effect of various conditions of heat shock on production of actinomycins by Streptomyces chrysomallus 2 and their composition was studied. The actinomycin biosynthesis was shown to be the function of the growing mycelium and changed in accordance with changes in the volume of the mycelium and its morphological features after heat shock at various suboptimal temperatures. The temperature shock had a specific action on the antibiotic synthesis: the index of the actinomycin maximum quantity increased after the heat shock at 35 and 38 degrees C and lowered more sharply than that of the biomass volume after the heat shock at the temperatures of 40, 42, 45 and 50 degrees C for 1 hour.

[The effect of heat shock on the growth and mycelial morphology of Streptomyces chrysomallus].

The effect of various conditions of heat shock (1 hour at 35, 38, 40, 42, 45 and 50 degrees C) on the growth and morphological features of Streptomyces chrysomallus, an organism producing actinomycin, was studied. A definite regularity in the mycelium morphological changes at high temperatures was observed. After the shock at 35 and 38 degrees C the biomass volume and morphological features of the streptomycete did not markedly differ from those in the control.

[Ionophore characteristics of heliomycin].

A highly purified product, identified as a well-known antibiotic geliomycin, has been derived by gradient extraction of the mycelium from Streptomyces robefuscus isolated from soil specimens as a result of purposeful search for a producer of hydrophobic ionophore antibiotics. The ionophore properties of geliomycin are highly labile and inducible. Cationic or anionic nature and the angle of the function performed depend on the concentration, type of electrolyte, protocol of measurements, and some additives used for the preparation of geliomycin electrodes to measurements.

[Gradient extraction of ammonium specific ionophore antibiotics from mycelium].

Streptomyces brunneofungs 118 and S.griseolus 224 were isolated from natural objects and shown to synthesize ammonium specific products belonging to macrotetrolide compounds. Gradient extraction was applied to the mycelium and it was demonstrated that the compounds were rather labile both in the native cells and on synthetic carriers and could be hydrolyzed by aqueous solutions of acetone and ethanol to various linear oligomers of narctinic acids.

[Antibiotic and electrochemical properties of some natural ionophoric compounds from streptomycetes].

The systematic position of 8 Streptomyces strains isolated from nature was determined as a result of purposeful search for producers of ionophore compounds; 7 of them belong to different species. Study of the antibiotic activity of these strains and of antibiotics isolated from them as crystals permit us to hypothesize that Streptomyces may be the test organisms most fit for production of hydrophobic ionophores from streptomycetes. Alteration of the ranges of cationic and anionic selectivity by using different electrolytes indicates a high lability of the natural ionophore compounds, which may be due to their physiological function: to take an active part in the exchange processes of all inorganic ions between the cell and environment.

[Directed search for streptomycetes that are producers of ionophoric antibiotics].

Streptomyces producing ionophore antibiotics were searched for in various natural substrata, such as soil, sea water, and coastline sea mud, in many geographical regions. A total of 393 Streptomyces strains were isolated, 308 of which proved to be capable of producing antibiotics; 135 of these contained water-insoluble antibiotically active substances in the mycelium. Studies by radioindication, spectrophotometry, and potentiometry demonstrated that these partially purified hydrophobic antibiotics possessed ionophore properties.

[UV-spectroscopic study of complex formation between nonactin and picrates of monovalent cations].

A macrotetrolide preparation including nonactin (about 75 per cent), monactin (about 23 pr cent) and traces of dinactin and trinactin was analyzed with the method of UV spectroscopy. It was shown to form hydrophobic complexes in organic solvents with picrates of univalent cations of ammonium, potassium and sodium. The complex strength depended not only on the cation nature, but also on the solvent and pH of the picrate aqueous solutions.

[Isolation and properties of macrotetrolide synthase from the mycelium of Actinomycetes].

The formation of cyclic polyester antibiotics (macrotetrolides) from nactinic acids in a cell-free system in the presence of a mycelium homogenate of Streptomyces chryzomallus var. macrotetrolidi, a producer of a complex of homologous macrotetrolide antibiotics, was demonstrated. An enzyme catalyzing the formation of an ester macrotetrolide ring and possessing a specific activity of 360 mumol/min/mg of protein has been isolated for the first time from the mycelium homogenate and purified 176-fold with a 18% yield.

[Enzyme activity of Bacillus polymyxa 153, the producer of polymyxin B, during sporulation and biosynthesis].

Metabolic properties of Bacillus polymyxa 153 were studied during vegetative growth, polymyxin B biosynthesis and active sporulation. In the cell extracts there was detected activity of exoproteases, endoproteases, tricarboxylic acid cycle dehydrogenases and pyruvate dehydrogenase. The enzymes activity in the cells growing into spores was higher than that in the cells of the vegetative developmental type.

[Directed synthesis of macrotetrolides].

The composition of the macrotetrolide complex was found to be strongly dependent on the conditions of the Streptomyces chrysomallus v. macrotetrolidi cultivation and could be varied by including in the medium 0.2% of organic acids, precursors of macrotetrolides, such as acetic, propionic and succinic.

[Intracellular ATP content and nonactin biosynthesis].

The effect of potassium orthophosphate on growth of the mycelium, its ATP contents and biosynthesis of the macrotetrolide antibiotic nonactin by Str. chrysomallus var. macrotetrolidi was studied.

[Effect of orthophosphate on the formation of the antibiotic nonactin].

The potassium orthophosphate added to the media with developing actinomycetes inhibits the nonactin macrotetrolide antibiotic but causes the increase of mycelium growth. The degree of inhibition depends on the quantity of orthophosphate and almost doesn't depend on the time of its adding to the actinomycetes culture. The degree of phosphorus consumption by actinomycetes is higher, the more its content in the media.

[Nonactin biosynthesis. The incorporation of precursors into the antibiotic molecule].

It was shown that 14C-glucose and 14C-acetate are incorporated with the mycelial suspension of Streptomyces chrysomallus var. macrotetrolidi into the macromolecular compounds of the biomass and into nonactin, an antibiotic of the macrotetrolide group. The dependence of the incorporation on the time of the mycelium incubation with the 14C-substrate was similar for both compounds.

[Carbon dioxide fixation by the mycelium of the actinomycete Streptomyces chrysomallus var. macrotetrolidi].

The mycelium of Streptomyces chryzomallus var. macrotetrolidi producing the macrotetrolide antibiotic nonactin was shown to be capable of carbon dioxide fixation. Carbon was found to be incorporated into nonactin and macromolecular compounds in the biomass.

[Biological action and complex-forming properties of a macrotetrolide antibiotic complex].

Macrotetrolide antibiotic complexes containing 60-80 per cent of nonactin were studied and their high antibacterial activity was shown. The macrotetrolides had a disintegrating effect on the bacterial membrane, which was evident from induction of the protoplast lysis and release of low-molecular compounds from the bacterial cells. The complex-forming properties of nonactin with respect to the ammonium, potassium and sodium ions were investigated in vitro.

[Macrotetrolide antibiotics from mycelia of Streptomyces chrysomallus].

White crystalline antibiotically active substances identified as macrotetrolides were isolated from the mycelium of four actinomycetous strains, i.e. S.

[Composition of cell walls of 2 mutant strains of Streptomyces chrysomallus].

The cell walls and peptidoglycans of two mutant strains, Streptomyces chrysomallus var. carotenoides and Streptomyces chrysomallus var. macrotetrolidi, were studied.

[Spore formation by Bacillus polymyxa during the inhibition of polymyxin biosynthesis].

When amino acids are added to the culture of Bacillus polymyxa growing under the conditions of active spore formation, the rate of polymyxin biosynthesis and the quantity of spores being formed decrease. All cells in the population start to produce spores under these conditions, but only some of them pass through all of the differentiation stages. Most of the cells remain in the state of prospores.

[Change in the ultrastructure of Bacillus polymyxa cells in the process of sporogenesis].

The fine structure of consecutive modifications was studied in sporulating cells of Bacillus polymyxa 153 growing in a liquid aerated medium. The stages of sporogenesis were found to be similar, in principle, with those in other species of the Bacillus genus, but also had certain peculiarities. In contrast to other bacilli, the nucleoid axial thread was not formed in B.

[Enzyme activity of an actinomycete producer of carotenes and macrotetrolides].

The activity of pyruvate dehydrogenase and dehydrogenases of the tricarboxylic acid cycle was assayed in the mycelium of Streptomyces chrysomallus var. Carotenoides growing under different conditions of the medium. The activity of the enzymes increased when acetic, citric and succinic acids were added at different periods of the growth.

[Electron microscopic study of Bacillus polymyxa in the developmental process and antibiotic formation].

The purpose of this work was to study growth of Bacillus polymyxa 153, biosynthesis of polymyxin by it, the formation of spores, and the fine structure of the cells. The antibiotic content was low in the cells and in the cultural broth during the first hours of growth and sharply increased later under the conditions of the medium ensuring the "vegetative" type of cultural growth. The cell wall reorganized, a periplasmic space appeared, and the membranous and mesosomal apparatus became more complicated in the cells actively synthesizing the antibiotic.

[Effect of K+ ions on Bac. polymyxa 153 growth and the biosynthesis of polymyxin B].

The growth of Bac. polymyxa, 153 producing polymyxin B did not change under the effect of various concentrations of potassium ions, while the antibiotic productivity of the cells significantly decreased. A great amount of polymyxin is excreted by the bacteria into the fermentation broth and a certain portion of the antibiotic remains in the cells.

[Antibiotic action on Bacillus polymyxa 153 enzymatic activity].

The study on the effect of some antibiotics on the activity of pyruvate dehydrogenase (PDG) and dehydrogenases of the tricarboxylic acid cycle (TAC) in the cell extracts of Bac. polymyxa 153 producing polymyxin B showed that the level of the reaction of the individual enzymes to the effect of various antibiotics was different. Specific sensitivity to polymyxins M and B was found in succinate dehydrogenase and that to polymyxin B in malate dehydrogenase.

[Separation of the biosynthesis products of a mutant strain of Actinomyces chrysomallus var. carotenoides and the identification of actinomycin antibiotics].

An orange antibiotically active substance isolated from the mycelium of a mutant strain of Actinomyces chrysomallus var. carotenoides was identified as a mixture of actinomycins according to its light absorption spectra, circular dichroism spectra, IR spectra and chromatographic comparison with the standard samples. A scheme for successive extraction of the biologically active substances from the mycelium resulting in isolation of a fraction enriched with antibiotic substances and a fraction enriched with pigments is presented.