Antibiotics formed by Actinomadura fulvescens

Novel antibiotics with in vitro activity against gram-positive bacteria were isolated from Actinomadura fulvescens INA 3321 and INA 3852. Conditions for biosynthesis and isolation of antibiotics 3321 and 3852, as well as their physicochemical and biological properties were studied. Chromatographic analysis of the antibiotics revealed that each of them contained two biologically active components. The components were separated with preparative chromatography. Physicochemical properties of the components showed that antibiotics 3321 and 3852 were similar. UV and IR spectroscopy suggested that antibiotics 3321 and 3852 were original compounds not described earlier.     

A new structural type of teichoic acid and some chemotaxonomic criteria of two species Nocardiopsis dassonvillei and Nocardiopsis antarcticus

The cell-wall teichoic acids of Nocardiopsis dassonvillei IMRU 509^T, IMRU 504 and IMRU 1250 and Nocardiopsis antarctius VKM Ac-836^T have the same unique structure that has not heretofore been found in bacteria. The polymer is built of 10 to 13 repeating units:

Screening of microbial secondary metabolites inhibiting cholesterol biosynthesis with the use of hepatoblastoma G2]

The culture of hepatoblastoma G2 (Hep G2) cells is proposed as an effective model for screening of microbial metabolites--inhibitors of sterol biosynthesis. This model can be applied at early stages of screening procedures and is quite effective for testing of crude extracts of producers' culture broth. The test is based on measurement inhibition of the radiolabelled precursors incorporation in cholesterol and separate fractions of lipids by microbial metabolites in Hep G2 cells. That allows not only to reveal inhibitors of cholesterol biosynthesis, but also to evaluate mechanism of action, including ability to inhibit the synthesis of cholesterol ethers. The cholesterol biosynthesis inhibition was tested at 150 microbial cultures (actinomycetes and imperfect fungi), isolated from soil. The ability to inhibit 14C-acetate incorporation into cholesterol was found in 15-20% of microbial cultures possessing antifungal activity of extracts (culture broth and mycelium).     

Formation of antibiotic 2562 by a culture of the actinomycete, Streptomyces griseovariabilis]

An actinomycetous culture 2562 inhibiting the growth of gramnegative bacteria was isolated from a soil sample. The culture was classified as Streptomyces griseovariabilis. It was found that culture 2562 produced an antibiotic belonging to the group of novobiocin. It consists of 2 components. One of them is identical to chlorobiocin and the other is a minor component of this group. Some parameters of the antibiotic complex production by strain 2562 under submerged conditions were studied. Nutrient media providing the predominant biosynthesis of the first (main) or the second component of the antibiotic were developed.     

New species, Actinomadura fulvescens sp. nov. and Actinomadura turkmeniaca sp. nov. and their antagonistic properties

Two new species of Actinomadura isolated from soil samples of the Turkmen SSR, i.e. Actinomadura fulvescens sp. nov. and Actinomadura turkmeniaca sp. nov. are described. The first species is characterized by formation of short (1-2 turns) spiral spore chains, smooth spores, scanty white aerial mycelium, colourless or yellowish substrate mycelium on synthetic media and brownish-yellow substrate mycelium and soluble pigment of the same colour on organic media. No melanoid pigment is secreted. The type culture is designated as INA 3321. The cultures of A. fulvescens show antibiotic activity. A. turkmeniaca is characterized by formation of short straight or spiral spore chains, smooth spores, scanty white aerial mycelium, substrate mycelium and soluble pigment of pinkish-violet colour, absence of melanoid pigment. The type culture is designated as INA 3344. The strains of this species have low antibiotic activity. The study on the use of carbon sources by the representatives of 7 species (9 strains) of Actinomadura showed that the majority of the cultures (5 species, 7 strains) produced no growth on the Pridham and Gottlieb medium (ISP-9) with various carbon sources, including glucose. Possibly this medium cannot be used as the main medium for investigation of the spectrum of carbohydrate consumption in Actinomadura.     

Effect of Lincocin Treatment on the Greening Process in Bean (Phaseolus vulgaris) Leaves

The effect of lincocin (a plastid protein synthesis inhibitor) treatment on the greening process of bean (Phaseolus vulgaris L.) leaves have been studied. In comparison with control leaves treated ones had a decreased rate of chloroplast development. They had a marked chlorophyll deficiency and a decreased chlorophyll a/b ratio. Some long and short wavelength forms of chlorophyll a were lacking as evidenced from the absorption spectra at 25°C and the fluorescence spectra at 77°K. The –¹⁴CO₂ fixation was inhibited by 80–90% in treated leaves. The fluorescence induced by the measuring light was greater in the treated leaves than in the control ones, and the kinetics of the decline of the relative fluorescence intensity were also different. Electron microscopic studies showed macrogranum-like structures and incomplete membrane vesicles in the treated plastids. After longer treatment a destruction of membranes was observed. The results indicate some structural and functional membrane deficiencies and instability of the membranes.     

Selective medium with nalidixic acid for isolating antibiotic-producing Actinomyces

The majority of actinomycetes belonging to various genera proved to be resistant to nalidixic acid concentrations having an inhibitory effect on bacteria with trailing growth i.e. B. subtilis and B. mycoides. The bacteria prevented isolation of actinomycetes as pure cultures. The use of a selective medium with nalidixic acid for isolation of soil actinomycetes resulted in 20 per cent increase in the number of the actinomycetes isolated as pure cultures. Preliminary treatment of the soil samples with calcium carbonate under moist conditions followed by the inoculation to the medium with nalidixic acid made it possible to increase isolation of actinomycetes at most 100-fold. With this complex method 495 actinomycete cultures were isolated, their antibiotic properties were studied and their taxonomic position at the genus level was determined. The complex method including the preliminary treatment of soil samples with calcium carbonate followed by inoculation to the selective medium with nalidixic acid is efficient and may be recommended for screening organisms producing new antibiotics.     

Lecithotrophic development and metamorphosis in the Indo-West Pacific brittle star Ophiomastix venosa (Echinodermata: Ophiuroidea)

Summary

The larval development of the ophiocomid ophiuroid Ophiomastix venosais described using SEM. The gastrula transforms into a uniformly ciliated early larva which progressively changes into a lecithotrophic late premetamorphic larva with a continuous bilateral ciliated band. This stage is short-lived and equivalent to a highly reduced ophiopluteus. Comparisons between O. venosa and other ophiuroid species whose development has been investigated suggest that, whatever the developmental mode (lecithotrophic or planktotrophic), a pluteus stage always occurs in ophiuroids with planktonic development. Two metamorphic stages were identified, the late metamorphic larva differing from the early one by the closure of the larval mouth. The appearance of the permanent mouth marks the end of the metamorphosis. The postlarva still possesses remnants of larval features. The transformation of the reduced ophiopluteus into a barrel-shaped metamorphic larva with transverse ciliated bands, a vitellaria larva, is followed. The possible occurrence of a unique type of metamorphic larva in non-brooding ophiuroids is discussed. Verification of this, however, needs further SEM investigations on metamorphic larva from species having “regular” planktotrophic development.     

Evaluation of the usefulness of three collections of bacteriophages for typing methicillin-resistant Staphylococcus aureus,isolated in Moscow hospitals

The typing of S. aureus methicillin-resistant strains, isolated in different hospitals of Moscow; was carried out with the use of three collections of phages: the International Set of Phages; the set of phages of the International Center of S. aureus phage typing in London (L); and the experimental collection of phages of the Gamaleya Institute of Epidemiology and Microbiology in Moscow (M). In this study made with the use of both the phages of the International Diagnostic Set and phages L in the standard typing dose of 1 TP about 6% of the cultures under study proved to be sensitive. When the typing dose was increased to 100 TP the phages of the international diagnostic set lyzed 75.5% of the cultures. The typed strains were found to belong to phage types 77 (71.7%), 77/84/85 (19.6%) and 94/96 (6.5%). At a concentration of 100 TP phages L lyzed 83.7% of the cultures, but the dominating phage types could not be determined due to a great variety of phage markers. In contrast to the two preceding collections, the third phage collection M was composed in such a way that in the study of the investigated culture the specificity of its restriction modification was primarily evaluated and only then the presence of antiphage immunity was determined. This latter collection was used in the evaluation of 93.1% of the cultures. By the specificity of their restriction specification system the majority of them were classified with two new groups, heretofore not described. Only this collection M made it possible to differentiate epidemic and sporadic strains and to evaluate the epidemic situation in all 6 hospitals.