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T G Volova

Publications and source records attributed to T G Volova.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

[Study of the dielectric permeability in the superhigh frequency range of a degraded polyoxybutyrate biopolymer].

The dielectric permeability of the degradable biopolymer polyhydroxybutyrate synthesized by hydrogen-oxidizing bacteria Alcaligenes eutrophus was investigated by the resonance method using original highly sensitive microstrip sensors. For the first time, a linear growth of dielectric permeability (delta epsilon/delta T = 7 x 10(-4) degree-1) due to the flexibility of the polymer chain in the temperature range from 10 to 70 degrees C was revealed. The energy of a bend of the nearest fragments was evaluated (E = 392 K), and its correspondence to the energies of bends of the alcyl groups of low-molecular substances like liquid crystals was established. It was shown that at low values of dielectric permeability in the high-frequency range (epsilon' = 2.25 +/- 0.02), which are stable, in a wide range of frequencies of the electromagnetic field (1 MHz - 1 Hz), polyoxybutyrate can be used in the microwave equipment.

Alcaligenes↗
PubMedDate not supplied

[Lipids from the green algae Botryococcus during staged growth in batch mode].

The lipid fraction of the green alga Botryococcus cultured in a batch mode was found to contain polar lipids (more than 50% of the total lipids), di- and triacylglycerides, steroids and their esters, free fatty acids, and hydrocarbons. In senescent culture, the content of polar lipids somewhat decreased and that of triacylglycerides increased by more than four times. The content of hydrocarbons in the algal biomass did not exceed 0.9% and depended little on the culture age. Intracellular lipids contained saturated and unsaturated (mono-, di-, and trienoic) fatty acids. The maximum content of C16:3 and alpha-C18:3 fatty acids (up to 35% of the total fatty acids) was detected in the phase of active growth. The extracellular and intracellular lipids of the alga differed in the proportion of particular lipids and in the fatty acid pattern.

Chlorophyta↗
PubMedDate not supplied

[Autotrophic synthesis of polyalkanoates by Alcaligenes eutrophus in presence of carbon monoxide].

The CO-resistant strain B5786 of the hydrogen-oxidizing bacterium Alcaligenes eutrophus was found to be able to synthesize polyhydroxyalkanoates (PHAs) under the conditions of growth limitation by nitrogen deficiency (the factor that promotes PHA synthesis) and growth inhibition by carbon monoxide. The gas mixtures that contained from 5 to 20 vol% CO did not inhibit the key enzymes of PHA synthesis--beta-ketothiolase, acetoacetyl-CoA reductase, hydroxybutyrate dehydrogenase, and PHA synthase. In the presence of CO, cells accumulated up to 70-75 wt% PHA (with respect to the dry biomass) without any noticeable increase in the consumption of the gas substrate. Chromatographic-mass spectrometric analysis showed that the PHA synthesized by A. eutrophus is a copolymer containing more than 99 mol% beta-hydroxybutyrate and trace amounts of beta-hydroxyvalerate. The PHA synthesized under the conditions described did not differ from that synthesized by A. eutrophus cells from electrolytic hydrogen.

Alkanes↗
PubMedDate not supplied

[The effect of temperature on the lipid composition of Botryococcus].

The lipid composition of the green alga Botryococcus was studied at three different cultivation temperatures: suboptimal, optimal, and supraoptimal. Cultivation at the supraoptimal temperature was found to considerably inhibit the synthesis of nearly all intracellular lipids, except for triacylglycerides, and to influence their fatty acid composition. In particular, the content of trienoic fatty acids was significantly lower at the supraoptimal than at the optimal cultivation temperature. At the same time, the fatty acid composition of the extracellular lipids of the alga virtually did not depend on cultivation temperature.

Chlorophyta↗
PubMedDate not supplied

[Tissue reactions to biodegradable suture materials from polyoxyalkanoates].

The paper presents data on the materials, methods, and results of a study of tissue responses in the postoperative period to implanted suture threads made of the polymer fatty acid derivatives (polyoxyalkanoates). These suture threads have been shown to have the required strength and meet a number of other requirements for currently available materials.

Animals↗
PubMedDate not supplied

[Biological properties of polyoxyalkanoates in chronic experiments in vivo].

Chronic experiments on mature Wistar rats studied the biological properties of suture threads from two types of polyoxyalkanoates (POA), such as polyoxybutyrate (POB) and the copolymer of POB and polyoxyvalerate (POV) (POB/POV) as compared to the conventional surgical material (silk and catgut). The physiological and biochemical parameters that reflect the status of the animals, including their behaviour, height and development, the weight of the body and viscera, the morphology of peripheral blood, the biochemical parameters of blood, the activity of some enzymes, as well as histological findings of the viscera, and lymphoid tissue responses were assessed. POA was found to produce no negative effect on the physiological, biochemical, and functional characteristics of the animals irrespective of the duration of contact with the internal medium of the body and of the chemical composition of a material.

Animals↗
PubMedDate not supplied

[Kinetic parameters of a culture of the hydrogen-oxidizing Ralstonia eutropha, grown under the regimen of biosynthesis of polyhydroxybutyrate].

Kinetic parameters of a culture of the hydrogen-oxidizing bacterium Ralstonia eutropha, grown on a gas substrate under the conditions favoring autotrophic biosynthesis of polyhydroxybutyrate, were studied. The following parameters, making it possible to control and optimize the process in industrial situations, were determined: specific rate of substrate consumption, physical properties of culture medium, and coefficients of heat emission and mass transfer.

Culture Media↗
PubMedDate not supplied

[Dynamics of activity of the key enzymes of polyhydroxyalkanoate metabolism in Ralstonia eutropha].

The dynamics of accumulation of polyhydroxybutyrate (PHB) and the activities of the key enzymes of PHB metabolism (beta-ketothiolase, acetoacetyl-CoA reductase, PHA synthase, D-hydroxybutyrate dehydrogenase, and PHA depolymerase) in the hydrogen bacterium Ralstonia eutropha B5786 were studied under various conditions of carbon nutrition and substrate availability. The highest activities of beta-ketothiolase, acetoacetyl-CoA reductase, and PHA synthase were recorded at the stage of acceleration of PHB synthesis. The activities of enzymes catalyzing PHB depolymerization (PHB depolymerase and D-hydroxybutyrate dehydrogenase) were low, being expressed only at stimulated endogenous PHB degradation. The change of carbon source (CO2 or fructose) did not cause any marked changes in the time course of enzyme activity.

Acetyl-CoA C-Acyltransferase↗
PubMedDate not supplied

[Study of Ralstonia eutropha culture producing polyhydroxyalkanoates on products of coal processing].

Kinetic indices of growth, polyhydroxyalkanoate (PHA) accumulation, and gas exchange have been studied in a culture of the carbon monoxide-resistant hydrogen strain Ralstonia eutropha B-5786 grown on a gaseous substrate (GS) obtained by lignite gasification. The GS was shown to be suitable for PHA production. To increase the degree of GS consumption, various modes of gas supply to the culture were tested. Based on the results, an algorithm was developed for calculating and controlling gas-exchange parameters in the PHA-accumulating culture of Ralstonia eutropha, grown on a new GS allowing high polymer yields (up to 75%) and degrees of the substrate utilization (up to 90%).

Carbon Monoxide↗
PubMedDate not supplied

[Physicochemical properties of two-component polyhydroxyalkanoates based on 3-hydroxybutyrate and 3-hydroxyvalerate].

A series of two-component polyhydroxyalkanoates consisting of hydroxybutyrate and hydroxyvalerate monomer at different ratios were synthesized using the bacterium Ralstonia eutropha B5786. The properties of polyhydroxyalkanoates were compared with those of the homopolymer of hydroxybutyric acid by X-ray structure analysis, IR spectroscopy, differential scanning calorimetry, and viscosimetry. With an increase in the molar fraction of hydroxyvalerate, an equalization of the ratio of the crystalline and amorphous phases in the copolymer was observed. The degree of crystallinity of the polymer decreased from 70-80 to 45-50%; in the range of an increase in the hydroxyvalerate molar fraction from several to 25-30 mol%, the dependence was linear. The temperature characteristics, the melting temperature (T(m)), and the degradation temperature (T(d)) were lower in polyhydroxyalkanoates than in polyhydroxybutyrate, for which T(m) and T(d) were 168-170 and 260-265 degrees C, respectively. In the copolymer, as the molar fraction of hydroxyvalerate grew, both parameters decreased. In the range of variation of monomer ratio studied, they decreased to 150-160 and 200-220 degrees C, respectively. No distinct correlation between the composition of the polymer and its molecular mass was found.

Butyrates↗
PubMedDate not supplied

[The synthesis of hydroxybutyrate and hydroxyvalerate copolymers by the bacterium Ralstonia eutropha].

The paper deals with the study of the synthesis of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) copolymers by the bacterium Ralstonia eutropha B-5786 grown under different carbon nutrition conditions (growth on carbon dioxide, fructose, and CO2-valerate and fructose-valerate mixtures). The parameters to be analyzed included the yield of biomass, the yield, synthesis rate, and composition of copolymers, the activity of the key enzymes of polyhydroxyalkanoate (PHA) synthesis (beta-ketothiolase, acetoacetyl-CoA reductase, and PHA synthase), the maximum tolerable concentration of valerate to the bacterium, and the conditions that govern the incorporation of hydroxyvalerate to copolymers. This allowed the relationship between cultivation conditions and the proportion of monomers in the copolymers to be deduced. We were able to synthesize a range of 3HB/3HV copolymers and found that the thermal characteristics and the degree of crystallinity of these copolymers depend on the molar fraction of 3HV.

Acetyl-CoA C-Acyltransferase↗
PubMedDate not supplied

[Physiological and biochemical characteristics and capacity for polyhydroxyalkanoates synthesis in a glucose-utilizing strain of hydrogen-oxidizing bacteria, Ralstonia eutropha B8562].

The physiological, biochemical, genetic, and cultural characteristics of the glucose-utilizing mutant strain Ralstonia eutropha B8562 were investigated in comparison with the parent strain R. eutropha B5786. The morphological, cultural, and biochemical characteristics of strain R. eutropha B8562 were similar to those of strain R. eutropha B5786. Genetic analysis revealed differences between the 16S rRNA gene sequences of these strains. The growth characteristics of the mutant using glucose as the sole carbon and energy source were comparable with those of the parent strain grown on fructose. Strain B8562 was characterized by high yields of polyhydroxyalkanoate (PHA) from different carbon sources (CO2, fructose, and glucose). In batch culture with glucose under nitrogen limitation, PHA accumulation reached 90% of dry weight. In PHA, beta-hydroxybutyrate was predominant (over 99 mol %); beta-hydroxyvalerate (0.25-0.72 mol %) and beta-hydroxyhexanoate (0.008-1.5 mol %) were present as minor components. The strain has prospects as a PHA producer on glucose-containing media.

Culture Media↗
PubMedDate not supplied

[Degradation of polyhydroxyalkanoates and the composition of microbial destructors under natural conditions].

The degradation dynamics of polyhydroxyalkanoates of different composition has been studied in an eutrophic storage reservoir for two seasons. It has been shown that the biodegradation of polymers under natural conditions depends not only on their structure and physicochemical properties but also, to a great extent, on a complex of weather-climatic conditions affecting the state of the reservoir ecosystem. The molecular genetic analysis of 16S rRNA has revealed bacterial species (clones) probably involved in the degradation of polyhydroxyalkanoates in a model storage reservoir.

Bacteria↗
PubMedDate not supplied

[Growth of Seliberia carboxydohydrogena carboxy bacteria with an altered composition of the gas mixture].

The growth and gas exchange of Seliberia carboxydohydrogena Z-1062 were studied in the regime of turbidostat when the conditions of gaseous nutrition were changed: a decrease in hydrogen concentration and an increase in carbon monoxide concentration, growth on two carbon sources (CO+CO2) and on two energy sources (H2+CO). The inhibition of the bacterial growth by CO was expressed in a decrease of the specific growth rate and in the reduced effectiveness of using a gaseous substrate. When the concentration of carbon monoxide was elevated from 0 to 40% and that of hydrogen was reduced from 80 to 40%, the specific growth rate of the cells was decreased from 0.4 to 0.04 h-1; here, the economic coefficient in terms of hydrogen fell from 3.6 to 0.62 g/g. The CO-oxidizing system of the bacterium was shown to be resistant. The rate of CO oxidation by the culture was from 0.6 to 0.8 L/h per 1 g of the synthesized biomass at the following concentration of gases in the medium (%); H2, 80-40; CO2, 5; O2, 15; CO, 10-40. The rate of CO oxidation by the culture rose when hydrogen concentration was decreased and CO concentration was increased.

Bacteria↗
PubMedDate not supplied

[Nutritional value of the proteins of carboxydobacteria].

The biological value of proteins from 3 carboxidobacterial strains was assessed on the basis of the protein amino acid content, consumption by the test-organism T. pyriformis and protein susceptibility to proteolytic enzymes in vitro. Carboxidobacterial proteins are characterized by a full-value amino acid composition and contain large amounts of all indispensable amino acids. This indicates that on the whole these proteins are quality ones. Experiments with the test-organisms have shown, however, that the relative biological value of the protein samples significantly yields to casein. The total digestibility of carboxidobacterial proteins by pepsin and trypsin in vitro is close to that of wheat vegetable proteins and lower as compared with that of casein. Carboxidobacterial proteins may be thus attributed to a protein group being an intermediate one between casein and wheat vegetable proteins.

Alcaligenes↗
PubMedDate not supplied

[Growth of hydrogen bacteria inhibited by carbon monoxide].

The growth of the hydrogen bacterium Alcaligenes eutrophys Z-1 was studied during inhibition by carbon monoxide in turbidostat. The specific growth rate of the bacterium was shown to depend on the concentration of CO in the gaseous phase. The deceleration of the cultural growth during inhibition by CO was accompanied with a decrease of economic coefficients with respect to oxygen and hydrogen. At a CO concentration of 10%, the specific growth rate of the bacterium was 0.25 hr-1 (mu) and the coefficient for utilizing the energy of hydrogen oxidation was 19.6% (eta); at a CO concentration of 20%, mu was 0.18 hr-1 and eta was 14.2%; at a CO concentration of 30%, mu was 0.07 hr-1 and eta was 10.2%. The deceleration of the cultural growth caused by inhibition with CO was not accompanied by changes in the synthesis of nitrogen containing and reserve substances in A. eutrophys Z-1. This strain of hydrogen bacteria was found to be resistant against extraneous microflora during inhibition with CO.

Alcaligenes↗