[Monitoring of microbial degraders in manned space stations].

Samples of microorganisms from the surface of constructions of Mir Space Station (Mir SS) were taken and examined after 13 years of operation. The following microorganisms were isolated and identified: 12 fungal species belonging to the genera Penicillium, Aspergillus, Cladosporium, and Aureobasidium; 3 yeast species belonging to the genera Debaryomyces, Candida, and Rhodotorula; and 4 bacterial species belonging to the genera Bacillus, Myxococcus, and Rhodococcus. The predominant species in all samples was Penicillium chrisogenum. It was shown that the fungi isolated could damage polymers and induce corrosion of aluminum-magnesium alloys. We commenced a study of microbial degraders on constructions of the Russian section of the International Space Station (RS ISS). Twenty-six species of fungi, bacteria, yeasts, and actinomycetes, known as active biodegraders, were identified in three sample sets taken at intervals. We founded a collection of microorganisms surviving throughout space flights. This collection can be used to test spacecraft production materials, in order to determine their resistance to biodegradation.

[Effect of cloned DNA fragment from Streptomyces chrysomallus No.2 on metabolism in Streptomyces strains]. / Vliianie klonirovannogo fragmenta DNK Streptomyces chrysomallus #2 na metabolizm riada shtammov streptomitsetov.

The effects on cloned DNA fragment carrying an actinomycin resistance determinant on physiological processes in streptomyces strains with various potencies in producing this antibiotic, their inactive mutants, and model strain of Streptomyces lividans 66 were studied. This fragment was shown to modulate bacterial resistance to actinomycin and biosynthesis of antibiotics.

[Biosynthes of polyketide antibiotics by various actinomycin producing Streptomyces species]. / Biosintez antibiotikov poliketidnoi prirody u razlichnykh vidov streptomitsetov--produtsentov aktinomitsinov.

A collection of actinomycin-producing Streptomyces strains, their variants with different levels of antibiotic biosynthesis, and recombinant strains were screened in order to select new strains that produce polyketide antibiotics. Screening with the use of the cloned act gene encoding a component of actinorhodin polyketide synthase (PKS) multienzyme complex from Streptomyces coelicolor revealed that many strains tested can synthesize polyketide antibiotics along with actinomycins. A relationship between biosynthetic pathways of actinomycins and polyketides is discussed.

[Activities of certain enzymes in blood of the Pleurodeles waltl newt]. / Aktivnosti nekotorykh fermentov v krovi tritona Pleurodeles waltli.

The goal of the study was to evaluate the physiological and biochemical status of Pleurodeles waltli (urodele amphibian) by monitoring enzymatic activity in blood plasma and/or lood cell components. The following enzymes were chosen: glutamate dehydrogenase (GDH), aspartate and alanine aminotransferases (GOT and GPT), superoxide dismutase, catalase, isocitrate dehydrogenase, and glucose-6-phosphate dehydrogenase. With the exception of GDH, GOT and GPT, enzymatic activity was noticeably higher in blood of females as compared to males. Reflecting destructive processes in organism, under normal conditions levels of GOT and GPT activity in plasma are very much equal in females and males. Differences in activities of the other enzymes were proportional to levels of steroid hormones in blood plasma of animals.

[Development of a system for cloning a DNA fragment, containing the determinant of resistance to actinomycin for Streptomyces chrysomallus No.2--a producer of actinomycin C]. / Razrabotka sistemy klonirovaniia fragmenta DNK, soderzhashchego determinat ustoichivosti k aktinomitsinu Streptomyces chrysomallus No. 2--produtsenta aktinomitsina C.

To study the modes of actinomycin biosynthesis and the mechanism responsible for resistance to the antibiotic producing S. chrysomallus No. 2, the authors undertook an examination and studies into the cloning system for gene(s) of resistance to actinomycin from a S. chrysomallus No. 2 actinomycin C producer and the cloning of a S. chrysomallus No. DNA fragment to the actinomycin-sensitive Streptomyces Sp. 26-115 H-I on the vector plasmid pIJ702. The cloning gave rise to actinomycin-resistant strains. The character of actinomycin resistance is inheritable in a steady fashion.

[Stability of Escherichia coli to the membranotropic antibiotic gramicidin S]. / Izuchenie ustoichivosti Escherichia coli k membranotropnomu antibiotiku gramitsidinu S.

The work was aimed at studying the effect of gramicidin S on the intact cells, spheroplasts and membrane specimens of Escherichia coli K12S with the natural resistance to this antibiotic. The resistance was shown to be caused by the barrier properties of the cell wall: the spheroplasts were highly sensitive to the lytic action of gramicidin S. The differences in the sensitivity to gramicidin S of substrate oxidation carried by the membranes of E. coli and Micrococcus luteus, a sensitive organism, were not of crucial significance for the manifestation of the resistance. The resistance was not associated with the decrease of gramicidin S adsorption: the cells were capable of binding large quantities of the antibiotic and remaining viable. Gramicidin S appeared to be attached to the cell walls (most likely, the outer membranes) rather than the cytoplasmic membranes.

[Changes in the permeability of streptomycete cytoplasmic membranes due to gramicidin S and its derivatives]. / Izmenenie gramitsidinom S i ego proizvodnymi pronitsaemosti tsitoplazmaticheskikh membran streptomitseta.

Exposure of intact mycelium and protoplasts of Streptomyces sp. 26-115 to gramicidin S resulted in impairment of permeability of the cytoplasmic membranes thus inducing a loss of low molecular compounds by the cells and protoplasts. Aminoacyl and guanyl derivatives of gramicidin S with respect to the delta-amine group of ornithine were somewhat less effective with respect to the streptomycete membranes. The same as the initial antibiotic, these derivatives had positively charged groups. The changes in the membranes of the streptomycete protoplasts induced by gramicidin S and its derivatives did not result in the protoplast lysis accompanied by decreasing of the suspension optical density. The neutral derivative having no positive charge and not capable of complexing with the membrane phospholipids and the carboxyl-containing derivative with a negative charge showed a low membrane activity when applied to the protoplasts and induced no impairment of permeability of the intact mycelium membranes. The use of phosphates as factors increasing the membrane activity of the gramicidin derivatives having no positive charge is not possible since in the presence of phosphates streptomycete protoplasts are readily destroyed.

[Optical density changes in bacterial protoplast suspensions exposed to membrane-active antibiotics]. / Izmenenie opticheskoi plotnosti suspenzii bakterial'nykh protoplastov pri deistvii membranoaktivnykh antibiotikov.

The effect of membrane active antibiotics, such as gramicidin S, its derivatives and carbonyl-conjugated pentaens on suspended bacterial protoplasts resulted in lysis of the protoplasts accompanied by a marked decrease in the optical density (OD) of the suspensions. However, when the drug concentrations were lower than those inducing the lysis, an increase in the suspension OD by 10-30 per cent as compared to the control values of the OD was often observed. The increase in the protoplast suspension OD was most pronounced with the use of the drugs with a relatively low lytic activity or under the conditions lowering the lytic activity of the antibiotics. Under such conditions no agglutination of the protoplasts was observed. The comparative estimation of the protoplast diameters by the method of Klenin et al. in the control suspensions of M. lysodeikticus protoplasts and in the suspensions with a stable increase in the OD showed that the OD increase was associated with swelling of the protoplasts: an increase in the suspension OD by approximately 30 per cent corresponded to an increase in the protoplast diameter by approximately 15 per cent. The observed increasing of the suspension OD must be due to the fact that the membrane active antibiotics induced a decrease in the osmotic stability of the protoplasts not sufficient for their lysis.

[DNA synthesis in relation to a varying vitamin B12 content in Propionibacterium shermanii cells]. / Sintez DNK v sviazi s razlichnym soderzhaniem vitamina B12 v kletkakh Propionibacterium shermanii.

The content of DNA in Propionibacterium cells is nearly twice as low at vitamin B12 deficiency comparing with normal cells. The rate of labeled adenine incorporation into the DNA depends on vitamin B12 content in the cells. The addition of adenosylcobalamin and thymine to the medium makes DNA content rise in the cells of the B12-deficient culture. The addition of thymine to a suspension of B12-deficient cells accelerates the incorporation of labelled adenine into DNA. The authors discuss the phenomenon of bacterial "unbalanced division" and the control of replication by changing the level of DNA precursors.