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B A Fikhte

Publications and source records attributed to B A Fikhte.

34 records · Page 2Linked to original sources
PubMedDate not supplied

[Isolation of Staphylococcus aureus protoplasts using lysoamidase].

The effect of the bacteriolytic enzyme preparation, lysoamidase, on Staphylococcus aureus 209P cells was studied. The protoplast formation was examined by spectrophotometric, biochemical and electron microscopic methods. Optimal conditions for isolation of S. aureus protoplasts were chosen. The susceptibility of S. aureus cells to lysoamidase depended on the culture age: the maximum effect was observed in the logarithmic growth phase. The protoplast yield was 80% when 1 M sucrose was used as an osmotic stabilizer. Lysoamidase caused local disruptures of the staphylococcus cell walls, which resulted in the formation of osmotically fragile spheroplasts and the release of protoplasts into the medium. The protoplasts obtained could retain 85-90% of the respiration activity and were able of cell wall regeneration.

Hydrolysis↗
PubMedDate not supplied

[Immobilization of E. coli cells in polyacrylamide-based microporous cryogels].

E. coli cells were immobilized in polyacrylamide cryogel by three ways: (1) introduction of cells in the reaction mixture followed by cryopolymerization; (2) the filling of the cryogel pores followed by cell fixation with diluted glutaric dialdehyde (GDA), and (3) the filling of the macropores of the polymeric matrix with modified surface. The ultrastructure of the gels and immobilized cells as well as distribution of attachment of the cells immobilized by different techniques were studied. The first type of immobilization was characterized by the highest quantity of the biomass in the gel (by protein) and by a sharp decrease of the cell viability. The second failed to retain the cells in the pores, and the GDA treatment significantly decreased the viability index. The latter technique was the mildest and completely maintained the viability of the population. However, the biomass content was lower as compared to the first type of immobilization, but could be considerably increased by the GDA treatment.

Acrylic Resins↗
PubMedDate not supplied

[Selection of Escherichia coli and Pseudomonas putida cultures with an enhanced resistance to immobilization on polyacrylamide gel].

Clones of Escherichia coli (A4, A70, G60) and Pseudomonas putida (A70, G30) with an elevated resistance to the process of immobilization in polyacrylamide gel and to the action of monomeric acrylamide were selected from the parent E. coli IBPM B115 and P. putida. The isolated cultures remained resistant to the above actions for a long time. The frequency at which cells with the elevated resistance appeared was comparable with the frequency of bacterial mutations. The plasmid analysis did not reveal the presence of plasmid DNA in the cells of the isolated cultures. The decrease in the viability index of bacterial populations caused by their immobilization in polyacrylamide gel and by the action of monomeric acrylamide did depend on the growth phase. The cells were more resistant to these actions in the stationary phase. The isolated cultures were more resistant as compared to the parent cultures irrespective of the growth phase.

Acrylamides↗
PubMedDate not supplied

[Effect of a deficiency of carbon, nitrogen, phosphorus and magnesium in the growth medium on the mechanical properties of Escherichia coli cell walls].

Values of modulus of elasticity of cell walls and strength level of cells Escherichia coli cultivated in the carbon, nitrogen and phosphorus deficient media or incubated in the magnesium-free medium were determined. Elastic modulus of cells grown in the magnesium-free medium was by two order of magnitude lower than that of the control cells. Elastic modulus of cells cultivated in the nitrogen and carbon deficient media was by one and two orders of magnitude lower than in the control cells whereas strength level was by 1.15 and 1.39 times higher, respectively. Elastic modulus of cells grown in the phosphorus deficient medium remained undetermined and strength level of those cells proved to be the lowest (0.9 of the control).

Carbon↗
PubMedDate not supplied

[Characteristics of free water distribution in the cytoplasm of cryotolerant cells of Cryptococcus laurentii].

The resistance to freezing-thawing was studied with Cryptococcus laurentii cultivated at a near-zero plus temperatures in a minimal or a rich medium. At the transition into the stationary phase, the resistance of the cells to freezing increased 20 times in the culture grown in the minimal medium and 8 times in the culture grown in the rich medium. Free water localization in the cell cytoplasm was determined by electron microscopy. In yeast cells with the maximal cryotolerance, free water was found mainly between glycogen granules. The authors discuss the role of glycogen as of a possible factor making the cells resistant to low temperatures.

Cold Temperature↗
PubMedDate not supplied

[Protective action of antioxidants on Escherichia coli cells immobilized in polyacrylamide gel].

The object of this work was to find out whether antioxidants could be used for weakening the effect of free radicals on Escherichia coli cells immobilized in polyacrylamide gel. Some of the antioxidants soluble in lipids and water (ionol, Epigid, glutathione) protected the cells against the action of free radicals produced in the process of acrylamide polymerization, and increased the viability of the immobilized bacteria.

Acrylic Resins↗
PubMedDate not supplied

[Effect on the orientation of the membrane vesicles of Escherichia coli of various methods of cell disintegration].

As was demonstrated using the Con-A polymer, membranous fractions prepared by various cell disintegration procedures are a heterogeneous population. The population includes right side out vesicles and inside out vesicles whose proportion depends on the procedure of disintegration. The orientation of these vesicles was studied by electron microscopy, their ATPase activity was assayed by cytochemical techniques, and the morphology of the vesicles was also investigated. The authors discuss the possible effect of Con-A on the reorganisation of membranes and the activity of ATPase.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Structural and biochemical characteristics of Escherichia coli cells with various levels of secretable alkaline phosphatase].

The biochemical and structural peculiarities of Escherichia coli cells with different rates of synthesis of secreted alkaline phosphatase were studied under the conditions of repression, derepression and constitutive synthesis. The enzyme synthesis was shown to correlate with the redistribution of free and membrane-bound ribosomes in the cells, with an increase in their proportion, and with a reconstruction of the cell ultrastructural organization.

Alkaline Phosphatase↗
PubMedDate not supplied

[Prediction of microorganism resistance to the immobilization process in polyacrylamide gel].

It is shown that the immobilization of bacterial cells in polyacrylamide gel or their exposure to monomer acrylamide results in a quantitatively similar decrease of their viability. It is indicated that acrylamide treatment may be used as a test for measuring the resistance of microbial populations to polyacrylamide gel immobilization and predicting the survival rate of microorganisms incorporated.

Acrylic Resins↗
PubMedDate not supplied

[Comparative characteristics of membrane preparations of Escherichia coli obtained by mechanical disruption].

Membrane preparations were obtained from Escherichia coli cells by the liquid and solid extrusion, ultrasonic treatment and ballistic disintegration. The preparations were subjected to biochemical analysis and studied by electron microscopy. The methods employed preserved, though to a different degree, the enzymic activity and integrity of the ribosome-membrane complex of the membrane preparations. The highest values were observed with the preparations obtained by ballistic and modified French-press disintegration. The membrane fractions obtained consisted of the cell wall and cytoplasmic membrane fragments heterogeneous in size and shape, and depending on the technique of disintegration were characterized by the presence or absence of a contact between them.

Cell Fractionation↗
PubMedDate not supplied

[Action of acrylamide on Escherichia coli cells].

The action of acrylamide on Escherichia coli B was studied: short-term action at high concentrations, long-term action at low doses under the normal conditions of growth and in the process of cell immobilization in polyacrylamide gel. Such a treatment was found to cause considerable structural changes in the cells. Division of the cells was inhibited and they reached giant sizes when grown in media containing 1-2% of acrylamide. The phenomenon might be used for differentiation of living and dead E. coli cells.

Acrylamides↗
PubMedDate not supplied

[Influence of various factors in polyacrylamide gel immobilization on the viability of Escherichia coli B cells].

The entrapment of an E. coli cell population into polyacrylamide gel (PAAG) is associated with a drastic decline of its viability. The effect of immobilization factors (the reagents used for PAAG preparation, their mixtures and the elevated temperature) upon the viability of the E. coli cell population was investigated by the method of microcultural analysis. It was found that all the components of the polymerization mixture, except for acrylamide, as well as the washed-off granules of polymerized del did not appreciably influence that viability of the cell population. Acrylamide at a concentration of 10% appeared very toxic. The decrease of its concentration to 5% and of the initial temperature of the polymerization mixture markedly lowered the toxic effect and, consequently, increased the viability of the population of immobilized E. coli cells.

Acrylic Resins↗
PubMedDate not supplied

[Cytochemical study of glycogen localization and accumulation in cells of the psychrophile Cryptococcus laurentii].

The synthesis and intracellular localization of glycogen were studied cytochemically on sections and by electron-microscopic cryofractography in the psychrophilic yeast Cryptococcus laurentii under different conditions of cultivation. Glycogen synthesis started in the phase of growth deceleration at the periphery of the cell at the same time as another reserve substance (lipid inclusions) was formed. The degree of glycogen accumulation in the cytoplasm depended on the composition of the medium and the temperature of growth. The maximal accumulation of glycogen in the cels was detected at a low growth temperature (4 degrees C) in a minimal medium. Under these conditions, glycogen was a predominant component in the cytoplasm at the stationary phase of growth, and was not noticeably utilized over a long period of time. The ribosomes were scattered in a diffuse manner between glycogen granules. The results are indicative of the fact that temperature plays a significant role in glycogen synthesis and that this carbohydrate is important for survival of yeast organisms at low temperatures.

Cryptococcus↗
PubMedDate not supplied

[Localization of the extracellular lipase in Candida paralipolytica yeasts].

The localization of lipase in the cells of Candida paralipolytica was studied for the first time by the techniques of electron cytochemistry and immunocytochemistry. Lipase is formed at the outer surface of the cytoplasmic membrane and often is confined to its invaginations. The reaction products were detected in individual parts of the periplasmic space, in the cell wall, and in its exofibrillar components. Apparently, lipase is formed on the ribosomal-membrane complex. The above pattern is observed only in the cells with a high lipase activity, but not in the control. The two techniques gave similar results. A series of electronograms are presented.

Animals↗