RESUMEN

Culture 78 was proposed as a neotype of Streptomyces ruber. It was isolated from the soils of the Baikal region and was closest, in its taxonomic properties, to the original description of the species [13] whose representative had been lost. Cultures from different microbial collections designated as S. ruber were shown to be unlike the original description. The neotype had the following taxononic properties: the cell wall of type I; spiral sporophores with extended spirals having 2-3 coils; oval spores with a smooth envelope; greyish pink aerial and dark-red substrate mycelia; a red pigment not passing into the medium; slow gelatin liquefaction and milk peptonization; weak starch hydrolysis; assimilation of glucose, xylose, rammose, fructose, and inositol; weak growth on arabinose, raffinose and mannitol, but not on sucrose; no formation of melanoid pigments; synthesis of riboflavin and prodigiosin pigments; inhibition of Gram-positive bacterial and acid-resistant mycobacterial growth; no inhibition of yeast and fungal growth. The culture was sensitive to streptomycin, neomycin, gentamycin, monomycin, tetracycline,erythromycin, oleandomycin, lincomycin, ristomycin, levomycetin, polymyxin and fusidin, but resistant in penicillin. The population was composed of six variants [3]: main, faded, asporogenic red, asporogenic yellow, asporogenic white and nocardia-like. The latter two were not capable of riboflavin and prodigiosin formation. The asporogenic yellow variant was a monosynthetic organism: it formed riboflavin, but could not synthesize prodigiosin. The neotype of S. ruber 78 is deposited withthe national Collection of Microorganisms (the reference number is VKM A-611).

Asunto(s)

RESUMEN

Clear antiviral activity of carbonyl-conjugated pentaene macrolides, such as flavofungin, mycothicin, brunefungin and flavopentin was shown on models with infectious and oncogenic viruses. The antibiotics were active against influenza A and B virus. The effect was most pronounced in the in vitro and in ovo systems. On a model of experimental influenza infection of mice with the lethal outcome, antiinfluenzal activity of flavofungin was comparable to that of remantadin. However, unlike the latter one flavofungin and brunefungin inhibited the growth of influenza B virus. The drugs had a pronounced inhibitory effect on variolavaccine virus and prevented formation of foci of cell neoplastic transformation infected with various strains of Rous sarcoma virus.

Asunto(s)

RESUMEN

The coefficients of distribution of flavofungin, flavopentin, nigrofungin and brunefungin, antifungal antibiotics, carbonyl-conjugated pentaenes, between water and Saccharomyces cerevisiae cells were determined. The coefficients were shown to increase with a decrease in the cell concentration. Therefore, the minimal concentrations of the antibiotics inhibiting the growth of S. cerevisiae decreased with a fall in the concentration of the yeast cells; the antibiotics with the greatest distribution coefficients had the lowest minimal inhibiting concentrations. The parameters for the binding of the antibiotics by the cells were determined using the equations of Scatchard and Klotz. It is possible that the binding mechanism for flavopentin and brunefungin differs from that for flavofungin and nigrofungin.

Asunto(s)

RESUMEN

When used in concentrations of 10-15 micrograms per 10(8) cells, flavofungin and nigrofungin, carbonyl-conjugated pentaenes lowered the rate of oxygen absorption by thymocyte suspensions in the presence of glucose. Flavopentin inhibited glucose oxidation in higher concentrations. ADP and succinate did not penetrate through the thymocyte membranes and were not oxidized with the cell suspensions. In concentrations of 30 micrograms per 10(8) cells the pentaenes did not change the membrane permeability for ADP. Still, they induced oxidation of succinate by the thymocytes (in the presence of amital). Flavofungin and nigrofungin were more effective with respect to increasing the membrane permeability for succinate as compared to flavopentin. The differences in the membrane permeability for various substrates induced by the antibiotics indicated a definite specific nature of the impairment of the thymocyte cytoplasmic membranes by carbonyl-conjugated pentaenes. The antibiotics tested are very similar as to their chemical structure and physicochemical properties. It is suggested that the differences in the biological activity of these substances are not associated with the presence of definite functional groups but are due to the general configuration of the antibiotic molecules, determining their hydrophilic-lipophilic balance and capacity for interaction with the biological membranes.

Asunto(s)

Asunto(s)

RESUMEN

The carbonyl-conjugated pentaenes flavofungin, nigrofungin and flavopentin exhibit considerable lytic activity toward Micrococcus lysodeikticus and Bacillus megaterium protoplasts. The antibiotics at concentrations of 5 to 14 microgram/ml cause lysis of 50% of the protoplasts within 15 min of their incubation. The antibiotics inhibit the activity of NADH oxidase and malate oxidase by 50% in the lysates of Micrococcus lysodeikticus and Bacillus megaterium protoplasts at concentrations of 30 to 50 microgram/ml; preincubation of the lysates with the antibiotics intensify the inhibiting action of the polyenes. Growth of the bacteria is inhibited when the minimal concentration of the polyenes is 75 to 100 microgram/ml. Interaction of the polyenes with bacterial membranes lacking sterols indicates that resistance of at least some bacteria to polyenes is caused by impermeability of the cell wall for these substances rather than by the absence of sterols in the membranes.

Asunto(s)

Asunto(s)

RESUMEN

It was found that fluorescence intensity of carbonyl-conjugated pentaens of flavofungin flavopentin and brunefungin in solutions depended on the solvent polarity and specific interactions of the antibiotics with the solvents. Addition of cholesterol into the aqueous solutions of these antibiotics resulted in a hypsochrome shift in their absorption spectra and increased fluorescence intensity. The antibiotics were found by their fluorescence in the yeast cells sensitive to them when their content was close to the concentrations resulting in the cell lysis. Low concentrations of the antibiotics resulted in changed localization of the yeast self fluorescence.

Asunto(s)

RESUMEN

Detailed studies of the taxonomical characteristics and the complex of produced antibiotics made it possible to establish the identity of Actinomyces albus var. fungatus, Solovieva et Rudaya, 1959 and Actinomyces tumemacerans, Krassilnikov et Koveshnikov, 1962. Both organisms produce a complex of antibiotics comprising albofungin, albonursin, and a polyene antibiotic belonging to the group of tetraenes. The cultures do not belong to the group of verticillate actinomycetes as was believed earlier (Krassilnikov, 1970). The later name, Actinomyces tumemacerans, is more appropriate since the organism described under the name of Act. albus var. fungatus differs sharply from other representatives of Act. albus and therefore cannot be regarded as its variety (nomen confusum). Actinomyces sp. RIA-248 producing albofungin differs from Act. tumemacerans P-42 as well as from Act. albus var. fungatus RIA-247 by the complex of produced antibiotics and other taxonomic properties. Apparently, it should be classed as a new species.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

Irradiation with solar rays of actinomycetes producing heliomycin changed the colour and UV-induced luminescence of the growth medium. This was caused by formation of a luminescent pigment, hydroxyquinone. The aerial mycelium reduced in spore formation acquired a pink colour.

Asunto(s)

RESUMEN

Luminescence of Actinomyces enissus synthesizing heliomycin is caused by the action of UV; it is multicoloured, mosaic, and changes in the course of growth. Multicoloured luminescence is due to formation of substances with various colours of luminescence (antibiotics heliomycin and resistoflavin, coproporphyrins I and III, riboflavin, etc.); its mosaic character is caused by the presence in the population of variants with difference in the component composition of luminescent substances and the degree of differentiation of colonies.

Asunto(s)

RESUMEN

Determination of heliomycin and resistoflavin contents in colonies of Act. resistomycilicus grown on pads with different density showed that the population density may be a factor controlling the level of the antibiotic biosynthesis by Act. resistomycificus and directing it along production of heliomycin or resistoflavin.

Asunto(s)

Asunto(s)

RESUMEN

The vegetative mycelium of a submerged culture of Actinomyces flavus 12 was studied by complex electron microscopy (negative and positive contrasting, cryofractography) in the course of biosynthesis of flavofungin. The antibiotic is accumulated first in the cytoplasm as singular small granules which later grow larger. Accumulation of flavofungin is accompanied with destruction of the cytoplasm, nucleoid and other structures. Secretion of the antibiotic is supposed to be accomplished according to holocrine type.

Asunto(s)

RESUMEN

The luminescence of Actinomyces lucensis producing etruscomycin was found to be caused not by the antibiotic but by additional luminescent substances. No direct correlation has been established between the content of the luminescent substances and the intensity of the luminscence. The latter depends on the differentiation of the colonies, i.e. on the presence of a dark layer that screens the luminescence of the colonial mycelium and is localized under the aerial mycelium. The dark layer contains pigments of the melanin type.

Asunto(s)

Asunto(s)

RESUMEN

Some characteristics of UV-induced luminescence were studied with Actinomyces olivocinereus producing the antibiotic heliomycin. The luminescence of the growth medium was found to be caused not by heliomycin, but by some other factors. The luminescence of heliomycin in the colonies was quenched as a result of its screening with melanin pigments located in a layer between the aerial and substrate mycelium.

Asunto(s)

Asunto(s)