[Effect of flavonoids on the composition of surface glycopolymers in Azospirillum lipoferum Sp59b].

Cultivation of the type strain Azospirillum lipoferum Sp59b in the presence of the flavonoid quercetin induced modification of the structure of the bacterial lipopolysaccharide. Cultivation in the presence of the flavonoid was shown to result in altered serological characteristics of the bacteria, increased heterogeneity of the outer membrane lipopolysaccharide pool, as well as in modified composition and fatty acid ratio of lipid A. The flavonoid was shown to induce the synthesis of the O-specific polysaccharide with the repeating structure represented by a tetrasaccharide consisting of a linear trisaccharide fragment of α-L-Rhap residues in the main chain and the terminal ß-D-Glcp residue. The structure of this O-specific polysaccharide was identical to the previously determined structure of the capsular polysaccharide of these bacteria grown without quercetin. Modifications in the structural composition of the capsular polysaccharide induced by cultivation in the presence of quercetin were revealed.

[Characterization of the lipopolysaccharides of serogroup II Azospirillum].

Lipopolysaccharides of six Azospirillum strains (A. brasilense SR50, SR80, SR88, SR109, SR111, SR115, and A. lipoferum SR 42) isolated from the rhizosphere of cereal plants of Saratov oblast, Russia and assigned to serogroup II by serological analysis were studied. In the lipid A fatty acid composition, the lipopolysaccharides under study were similar to those of other Azospirillum strains and were characterized by predominance of 3-hydroxytetradecanoic, 3-hydroxyhexadecanoic, and octadecenoic acids. Monosaccharide analysis of the O-specific polysaccharides (including determination of the absolute configurations, methylation analysis, and one- and two-dimensional NMR spectroscopy) revealed the presence of two types of repeating units in varying ratios. High degree of serological similarity between the strains under study was shown to result from the presence of repeating units with identical structure in their O antigens.

Structural peculiarities of the O-specific polysaccharides of Azospirillum bacteria of serogroup III.

Lipopolysaccharides and O-specific polysaccharides were isolated from the outer membrane of bacterial cells of three strains belonging to two Azospirillum species, and their structures were established by monosaccharide analysis including determination of the absolute configurations, methylation analysis, and one- and two-dimensional NMR spectroscopy. It was shown that while having the identical composition, the O-polysaccharides have different branched tetrasaccharide repeating units. Two neutral polysaccharides were found in the lipopolysaccharide of A. brasilense 54, and the structure for the predominant O-polysaccharide was determined. The structural data, together with results of serological studies, enabled assignment of strains examined to a novel serogroup, III. The chemical basis for the serological relatedness among the azospirilla of this serogroup is presumably the presence of a common →3)-α-L-Rhap-(1→2)-α-L-Rhap-(1→3)-α-L-Rhap-(1→ oligosaccharide motif in their O-polysaccharides.

[Determination of phage resistance of E. coli cells with electrooptical analysis of cell suspensions].

Changes in the electrooptical (EO) properties of cell suspensions of the E. coli strains: XL-1, BL-Ril, TG-1, K-12, B-878, and BL-21 (DE) in their contamination with the bacteriophage M13K07 were studied depending on the time of infection. The phage-induced specific changes in the EO parameters of cell suspensions were ascertained to occur only in the E. coli strains XL-1, TG-1, and K-12 whereas these changes were not seen in the cell suspensions of E. coli strains BL-Ril, B-878, BL-21 (DE). Control experiments were carried out to infect the cells with the bacteriophage, by making a standard inoculation of the dense nutrient media. The fact that the method for EO analysis of cell suspensions may be used to determine the phage resistance of microbial cells is first shown.

Capsular polysaccharide of the bacterium Azospirillum lipoferum Sp59b: structure and antigenic specificity.

Antigenic differences were revealed between the cell wall outer membrane lipopolysaccharides and the capsular high molecular weight bioglycans for a typical strain of the nitrogen-fixing rhizobacterium Azospirillum lipoferum Sp59b using antibodies prepared against the homologous lipopolysaccharide and lipopolysaccharide-protein complex. From the capsular lipopolysaccharide-protein and polysaccharide-lipid complexes of A. lipoferum Sp59b, polysaccharides were isolated and their structure was for the first time established in Azospirillum by monosaccharide analysis which included determination of the absolute configurations, methylation, O-deacetylation, and one- and two-dimensional NMR spectroscopy. The polysaccharides of the capsular complexes were shown to have identical structure of the branched tetrasaccharide repeating unit, which differs from the structure of the O-specific polysaccharide within the outer membrane lipopolysaccharide of this strain.

[Electrooptical properties of the microbial suspensions during a cell's interaction with the antibodies of a different specificity].

The electrooptical abilities of the microbial suspensions during a cells interaction with antibodies (ABs) of a different specificity have been studied on the example of the Azospirillum brasilense Sp245 cells and their interaction with the polyclonal monospecific and polyspecific antibodies. Measuring of the orientational spectra of the cells has been performed using the ELUS electrooptical analyzer. A discrete frequency set of an orienting electric field (740, 1000, 1450, 2000, and 2800 kHz) was used. It has been shown that an interaction of the polyspecific AB with the investigated cells redoubles the value of an electrooptical signal of the cells' suspension as compared with the monospecific antibodies. These findings can be used for a development a new method of microorganism detection.

[Composition and immunochemical characteristics of exopolysaccharides from the rhizobacterium Paenibacillus polymyxa 1465].

Exopolysaccharides (EPS) synthesized by Paenibacillus polymyxa 1465 in the course of batch cultivation were proven to contain neutral and acidic fractions. EPS are heterogeneous polysaccharides, represented by a complex of macromolecules with molecular mass of 7 x 10(4) to 2 x 10(6) Da. The acidic component was shown to be predominant in EPS preparations isolated from bacteria cultivated on glucose, which corresponds to a higher viscosity of EPS water solutions. The exoglycans were shown to contain glucose, mannose, galactose, and uronic acids. Polyclonal rabbit antibodies against the isolated P. polymyxa 1465 EPS preparations were used in a comparative immunodiffusion analysis of a number of P. polymyxa strains.

[Degradation of hydrocarbons and their derivatives by a microbial association based on Canadian pondweed].

The degrading action of an aquatic plant-microbial association on the base of Canadian pondweed (Elodea canadensis) and its components (sterilized plant and two periphytonic strains, Pseudomonas fluorescens E1-2.1 and Brevundimonas diminuta E1-3.1) on crude oil, the water-soluble crude oil fraction, and individual test compounds (phenol, toluene, benzene, decalin, and naphthalene) was studied. It was found that the native association had a wider range and higher degree of degrading activity than individual species. Bacterial strains were significantly more active only towards naphthalene. The ability of the sterilized plant to degrade crude oil and phenol was no less than that of microorganisms and much more for toluene. Enzymatic activity towards the pollutants studied was found in E. canadensis exudates and buffer extracts of its cells.

[Electrooptical parameters of kanamycin-treated E. coli cell suspensions].

The effect of kanamycin on the electrophysical parameters of cell suspensions of Escherichia coli K-12 and pMMB33 was investigated. Incubation of the sensitive K-12 strain with kanamycin resulted in significant changes in the orientation spectra (OS) of the cell suspensions; these changes were not revealed in the case of the resistant pMMB33 strain. In the case of the sensitive K-12 strain incubated with different kanamycin concentrations, changes in the OS of the cell suspensions occurred within the 10-1000 kHz frequency range of the orienting electrical field. The most pronounced change in the electrooptical signal was observed at 10 microg/ml of kanamycin. Control experiments were carried out by standard plating on nutrient media. Thus, the OS changes of suspensions in the presence of antibiotics may be used as a test for microbial resistance to such antibiotics.

[Chemical and serological studies of liposaccharides of bacteria of the genus Azospirillum].

The analysis of the lipopolysaccharides (LPS) of nine strains of azospirilla revealed the presence of the characteristic components of these glycopolymers: carbohydrates, hydroxylated fatty acids, and 2-keto-3-deoxyoctonic acid (KDO). SDS electrophoresis revealed the heterogeneous nature and the strains differences in the ratio of the molecular S and R forms present in the LPS. Polyclonal rabbit antibodies (Ab) were obtained against the isolated LPS(Cd), LPS(Sp59b), LPS(Sp7), LPS(S17), and LPS(KBC1) preparations. Based on the results of the serological studies of the LPS, the bacterial strains investigated in the work were divided into two main serogroups. Based on the immunoblotting data, Ab(Sp59b) and Ab(Cd) were found to be formed in response to both the S and R forms of the LPS molecules, whereas all the rest formed in response to the S forms only. It was shown that the heterogeneity of the antigenic determinants is typical of the second LPS group. It was suggested that rhamnose plays one of the key roles in the specific interactions between the azospirillum membrane LPS and Ab.

[Role of the clasping-leaved pondweed (Potamogeton perfoliatus) polysaccharides in formation of its bacterial environment].

The effect of the polysaccharides of clasping-leaved pondweed (Potamogeton perfioliatus) on the formation of a bacteriocenosis of this plant was demonstrated by research on chemoreception, relative surface hydrophobicity, and the growth characteristics of the members of five bacterial genera abundant in this microbiocenosis. The plant heteropolysaccharides of anionic and cationic nature were found to participate in selective stimulation or inhibition of growth of some microbial groups in surrounding water. These findings improve our understanding of the spectrum of physiological activity of glycopolymers of diverse origin.

Investigation of enzymatic degradation of pectin polysaccharides under limiting conditions.

The dynamics of changes in spectra of oligosaccharide fragments formed during enzymatic degradation of plant pectins at low enzyme/substrate ratio was studied. It is shown that degradation of deesterified pectin molecules is a discrete and determined process manifested in establishment of a stable polysaccharide spectrum. It is noted that introduction of chemical modifications into the polysaccharide substrate structure preserves the discreteness of the polymer molecule fragmentation but changes the spectrum of formed oligosaccharide fragments. It is supposed that degradation is defined by the spatial (three-dimensional) organization of the polysaccharide molecule.

Effects of prenatal and neonatal cadmium intoxication on the intensity of lipid peroxidation and activity of glutathione system in progeny of albino rats.

Oral treatment of pregnant or lactating rats with Cd(NO3)2 in a dose of 2 mg/kg increased plasma and erythrocyte levels of MDA and reduced glutathione, activities of glutathione-S-transferase, glutathione reductase, and gamma-glutamyl transferase in their 4-month-old progeny. Changes in the function of glutathione system and LPO intensity after cadmium intoxication during the neonatal were less pronounced than after prenatal exposure.

[Dynamics of the changes of electrophysical properties of Azospirillum brasilense Sp7 cells at their binding with wheat germ agglutinin].

The electrooptical properties of Azospirillum brasilense Sp7 cell suspensions have been studied at a specific interaction with wheat germ agglutinin (WGA), using the dependences between the changes of optical densities of cell suspensions at the electric orientation of cells and the orienting field frequencies of 740, 1000, 1450, 2000, and 2800 kHz. It was shown that the electrooptical (EO) properties of cell suspensions changed at the interaction ofA. brasilense Sp7 cells with WGA and that the EO signal value changed irrespective of the cultivation conditions. At the same time, the dynamics of the changes of the EO properties of microbial suspensions was different for microbial cells grown under different conditions. It may be evidence of the differences in the cell surface properties of microbial cells, and of the dependence between bacterial response to lectin and growth conditions. The possibility of using the EO analysis of bacterial suspensions for the study of the high-specific binding of polypeptide molecular signals with the bacterial target cells and for assessment of the dynamics of this process has been demonstrated.

[Changes in electrophysical characteristics of Azospirillum brasilense Sp7 cells during their interaction with polyclonal antibodies].

Electrooptical characteristics of Azospirillum brasilense Sp7 cells during their specific interaction with polyclonal rabbit antibodies were studied. Dependence of optical density of cell suspension during electroorientation of cells from frequency of orienting field in interval 10, 100, 250, and 500 kHz was evaluated. Itwas shown that electrooptical (EO) characteristics of bacterial suspensions change during interaction of A. brasilense cells with antibodies, and maximal changes occur when frequency of oriented field amounts 100-250 kHz. During interaction of A. brasilense Sp7 with strain-specific polyclonal antibodies in the presence of Escherichia coli K-12 and Pseudomonas putida C-11 decrease of amplitude of analytic signal was observed but detection of A. brasilense Sp7 cells was possible. Possibility of detection of microorganisms by EO analysis during their interaction with antibodies was shown.

[Electrooptic analysis for investigation of antibiotics synergistic action with respect to Escherichia coli].

The effect of ampicillin and kanamycin on the electrophysical properties of Escherichia coli K-12 was studied. Significant changes in the orientation spectra of the cell suspensions incubated with various concentrations of the antibiotics were observed only at the first five frequencies of the orienting electric field (10-1000 kHz). Ampicillin in a concentration of 1.0 mcg/ml and kanamycin in a concentration of 0.5 mcg/ml practically had no effect on the value of the electrooptic (EO) signal of the cells of the strain susceptible to the antibiotics. However, a significant change in the EO signal was recorded, when the cells were incubated in the presence of both ampicillin (1 mcg/ml) and kanamycin (0.5 mcg/ml), that was due to the synergistic effect of the antibiotics. Therefore, possible registration and investigation of antibiotics synergistic effect by electrooptic analysis of cell suspensions was shown, which suggested that electrooptic methods were rather efficient in control of antibiotic action on microorganisms.

[Chemical composition and immunochemical characteristics of the lipopolysaccharide of nitrogen-fixing rhizobacterium Azospirillum brasilense CD].

The chemical composition of the lipopolysaccharide of the associative diazotrophic rhizobacterium Azospirillum brasilense Cd has been studied. Among the main components of the hydrophobic part of the lipopolysaccharide, we identified 3-hydroxytetradecanoic, hexadecenoic, 3-hydroxyhexadecanoic, hexadecanoic, octadecenoic, and nanodecanoic fatty acids; the carbohydrate part contained rhamnose, galactose, and mannose. Polyclonal antibodies against the preparation under study were raised in rabbits. Serological relations between A. brasilense Cd and other strains of Azospirillum spp. were studied using double radial immunodiffusion and enzyme-linked immunosorbent assay.

[A bioelectrochemical study of a suspension of Escherichia coli cells metabolizing glucose and lactose].

The metabolism of glucose and lactose in E. coli K-12 cells has been studied using a bioelectrochemical (BEC) approach. The magnitude and the duration of the response of a BEC anode were found to be functions of the composition of nutrient media and the concentration of bacterial cells. The amount of electricity that is generated enzymatically during the metabolism of a particular substrate depends on the activity of the relevant enzymes. This suggests that the BEC approach can be used for evaluating the activity of particular enzyme systems.

[Electrooptic analysis of Escherichia coli cell suspension for assessment of antibacterial activity of levomycetin].

Influence of chloramphenicol on electrophysiologic charateristics of Escherichia coli strains susceptible (K-12 strain) and resistant (pBR-325 strain) to it has been studied. It has been shown that incubation of susceptible bacteria with chloramphenicol leads to significant change of magnitute of electrooptic (EO) signal. Significant changes in orientantional spectra of suspensions of susceptible to chloramphenicol cells incubated with different concentrations of antibiotic were observed only on first five frequencies of orienting electric field (10 - 1000 kHz). Maximal change of EO signal occurred at chloramphenicol concentration 35 mg/ml and it didn't depend on the time of antibiotic exposure. Incubation of resistant strain pBR-325 with chloramphenicol did not lead to change of EO parameters of cell suspension. Potential for use of electrophysical analytic methods for assessment of antibacterial activity of chloramphenicol to control effect of antibiotics on microorganisms has been proposed.