Study of the fructosediphosphate aldolase and transketolase activity in the nystatin producer, Actinomyces noursei]

Activity of transketolase, an enzyme of the pentose cycle and fructosodiphosphataldolase, an enzyme of glycolisis was studied in the dynamics of development of the nystatin-producing organism and its inactive mutant under various conditions of their cultivation with a purpose of finding relation between the antibiotic production and general metabolism of Act. noursei. The transketolase activity of the organism was 2-4 times higher than that of the inactive mutant. Addition of 8000 Units/ml of nystatin to the medium markedly suppressed (50-100 per cent) the aldolase activity, however it had no effect on the transkelotase activity. Possibly the antibiotic accumulated in the mycelium played the role of a regulator of the activity of the enzymes, directing the metabolites along the hexosomonophosphate pathway of carbohydrate dissimilation.     

Some characteristics of fucidin biosynthesis]

Some features of fusidin biosynthesis by 2 strains of Fusidium coccineum were studied proceeding from the peculiar properties of the antibiotic molecule structure. It was found that an increase in the levels of the carbon sources in the medium stimulated the biosynthesis of fusidin, while excessive concentrations of nitrogen especially in its inorganic and amino acidpeptide forms stimulated the organism growth and lowered the antibiotic activity levels. The concentration of nitrogen in the medium is considered as one of the possible control mechanisms in the processes of the fungus growth and biosynthesis of fusidin.     

Directed biosynthesis of proteolytic enzymes in Actinomyces thermovulgaris]

The biosynthesis of proteolytic enzymes in the thermophilic culture of Actinomyces thermovulgaris, strain T-54, was directed by changing the composition of the medium and the temperature of cultivation. A temperature of 40 degrees C is optimal for the growth and production of neutral and alkaline proteases. The maximum activity of acid proteases was found during the growth on a complex medium at 30 degrees C. An increase of temperature to 50 degrees C during the cultivation of the microorganism on a chemically defined medium resulted in its secondary growth and a sharp rise in the activity of alkaline and neutral proteases.     

Lysogeny in heat-tolerant hydrocarbon-oxidizing actinomycetes of species Actinomyces griseomycini]

Six strains of thermophilic hydrocarbon-oxidizing Actinomyces griseomycini were tested for lysogeny. The lysogenic state was detected in the four strains and their phages were isolated. The phages isolated from the three strains were virulent and cause lysis of the host culture. All isolated phages were specific and did not cause lysis of other actinomycetes species. However, the phages had different activity towards the six studied strains of Actinomyces griseomycini. One phage induced lysis only of its indicator culture, other phages caused lysis of four strains, including those two from which no phage was isolated. All phages produced negative colonies of identical morphology. The morphology of their particles was also the same. The phages induced cross-resistance and were characterized by thermoresistance.     

Intrinsic luminescence and differentiation in Actinomyces lucensis--producer of etruscomycin]

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.     

Comparative evaluation of various bacterial growth inhibitors as selective agents for isolation of soil Actinomyces]

Tobramycin and dioxidine sensitivity of 57 strains belonging to 14 actinomycetes genera was studied. The cultures of Streptomyces were much more sensitive to tobramycin than the cultures of rare genera. The majority of the Streptomyces cultures showed a high resistance to dioxidine (MIC greater than or equal to 50 micrograms/ml). At the same time the majority of the cultures of rare genera were inhibited by low concentrations of dioxidine (no more than 50 micrograms/ml). For isolation of actinomycetes from soil samples, tobramycin, dioxidine, ceftriaxone and novobiocin were used. Tobramycin added in a concentration of 10 micrograms/ml to the Gauze agar organic medium No. 2 promoted a 2-fold increase in detection of actinomycetes of the rare genera as compared to the control. It was especially favourable for detection of cultures belonging to Micromonospora, Amycolatopsis, Streptosporangium and Nocardiopsis. Dioxidine in concentrations of 10 and 50 micrograms/ml inhibited the growth of the cultures belonging to rare genera. Ceftriaxone in the same concentrations inhibited the growth of the cultures of both Streptomyces and the rare genera. Novobiocin favoured detection of the cultures belonging to Amicolatopsis and Micromonospora. Therefore, among the tested compounds tobramycin and novobiocin appeared to be the most useful selective agents for isolation of actinomycetes of rare genera.     

Actinomyces in cervical smears of women using intrauterine contraceptive devices

Cervical smears from 1,784 women who attended the family planning clinics of the Institute for Research in Reproduction were examined for the presence of Actinomyces-like organisms. Among 815 intrauterine contraceptive device (IUD) users, the repeat smears from 57 women were positive for Actinomyces-like organisms, giving a prevalence rate of 6.99%. Immunofluorescent staining using specific antisera confirmed the presence of A. israelii in all 57 women. Forty IUD users whose smears were positive for Actinomyces-like organisms underwent bacteriologic culture studies; A. israelii was isolated in 23 of these cases. The clinical findings at the time of smear collection in the 57 IUD users were within normal limits. The initial cervical smears of all IUD users and both the initial and repeat smears of all nonusers were negative for Actinomyces-like organisms. The data indicate that prolonged use (greater than 2 years) of an inert or copper intrauterine device promotes the overgrowth of Actinomyces in the vagina and that this can be detected by routine cervical cytology.     

Reclassification of Corynebacterium pyogenes (Glage) in the genus Actinomyces, as Actinomyces pyogenes comb.nov

Corynebacterium pyogenes (Glage) differs to such an extent from the type species of Corynebacterium, Corynebacterium diphtheriae (Lehmann and Neumann), that it cannot be retained in this genus. Numerical phenetic and chemical data indicate a close relationship between Corynebacterium pyogenes and the species Actinomyces bovis (Harz). It is proposed that Corynebacterium pyogenes be reclassified in the genus Actinomyces, as Actinomyces pyogenes (Glage) comb.nov.     

Some characteristics of perlite as an experimental growth medium

Solution flow rate is an important factor to be considered when designing or operating flowing culture equipment. A theoretical model is developed showing that the actual flow rate required for a particular experiment will depend upon many factors, important among which are the nature and concentration of the ion under consideration, the quantity of roots per pot, and the efficiency of these roots in absorbing the test ion under the conditions of the experiment. The results of experiments conducted at low concentrations of ammonium and nitrate nitrogen clearly demonstrate that flow rates of the order of 1 litre per pot per minute or greater may be required to prevent excessive depletion of the nutrient solution. At lower flow rates, solution depletion resulted in substantial reductions in growth and nitrogen uptake. Quantities of nutrient solution required for experiments at very high flow rates can be reduced to practical levels by the use of recirculating flowing culture systems, even in installations containing large numbers of pots.     

Some quantitative characteristics of the frog retinal rod outer segments]

Retinal rod outer segments in frogs were studied by means of light microscopy, refractometry, microspectrophotometry, and electron microscopy. Analysis of the data obtained shows that an unidentified substance, which makes up about 50% of outer segment dry weight, is lost during routine biochemical investigations. The protein parts of the rhodopsin molecules make up 85% of the outer segments proteins and 25% of outer segment dry weight. Rhodopsin molecules can be arranged in a square array with a unit cell side of about 7 nm on one side of each disk membrane. Lipids in a single membrane occupy only 2 nm, and disk membranes are strongly hydrated.     

Effect of Actinomyces rimosus ribonuclease on the reproduction of viruses]

Antiviral activity of RNA-ase isolated from the fermentation broth of Actinomyces rimosus was studied. The effect of the enzyme on multiplication of the viruses of vesicular stomatitis, Newcastle and cariolovaccine diseases was investigated. It was found that the enzyme was capable of suppressing reproduction of the vesicular stomatitis virus (VSV) in the culture of chick fibroblast cells. The suppression level directly depended on the enzyme concentration and decreased with an increase in the infection multiplicity. The enzyme had no effect on multiplication of other viruses tested. RNA-ase decreased the infectious properties of the freshly isolated virus-containing material in concentrations showing the antiviral effect. Preliminary incubation of the cells with the enzyme resulted in suppression of the plaque formation by VSV. The RNA synthesis in such cultures treated with RNA-ase was somewhat lower. It was shown that the antiviral effect of RNA=ase was connected with its enzymic activity. RNA-ase has no antiviral effect in the experiments with mice infected with VSV.     

Study of the structure of colonies of active and inactive Actinomyces parvullus variants using luminescence and scanning microscopy]

The colony structure of the active and inactive proactinomycete-like variants of Actinomyces parvullus producing actinomycin D was studied with luminescent and scanning microscopy. Clear differentiation of the colony profile was shown by the structure and functions of the mycelium layers. A zone of active synthesis and accumulation of the antibiotic was observed in the colonies of the active variant in the upper part of the substrate mycelium with reddish-yellow self luminescence in UV light and characteristic close hyphae "cemented" by the intracellular substance. Formations of the granule type were often noted on the hyphae of that layer. The layer of the aerial mycelium was loosely connected with the substrate mycelium and consisted of sporophores and spore chains partially broken into single spores. The colonies of the inactive proactinomycete-like variant had a slightly differentiated profile with a sponge-like structure, no zones of the antibiotic synthesis being found. The presence of the intracellular substance was observed in the upper part of the colony supersubstrate mycelium.