Antimicrobial Activity of Geometric Isomers of Etherolenic Acid-the Products of Plant Lipoxygenase Cascade.

Data on the influence of the double bond geometry on the antimicrobial properties of different isomers of etherolenic acid against phytopathogenic bacteria are presented. (ω5Z)-Etherolenic acid possesses bactericidal properties against Xanthomonas campestris ssp. vesicatoria, Pseudomonas syringae ssp. tomato, Pectobacterium atrosepticum SCRI1043; the etherolenic and (11Z)-etherolenic acids possess only bacteriostatic properties.

Pathogen-induced conditioning of the primary xylem vessels - a prerequisite for the formation of bacterial emboli by Pectobacterium atrosepticum.

Representatives of Pectobacterium genus are some of the most harmful phytopathogens in the world. In the present study, we have elucidated novel aspects of plant-Pectobacterium atrosepticum interactions. This bacterium was recently demonstrated to form specific 'multicellular' structures - bacterial emboli in the xylem vessels of infected plants. In our work, we showed that the process of formation of these structures includes the pathogen-induced reactions of the plant. The colonisation of the plant by P. atrosepticum is coupled with the release of a pectic polysaccharide, rhamnogalacturonan I, into the vessel lumen from the plant cell wall. This polysaccharide gives rise to a gel that serves as a matrix for bacterial emboli. P. atrosepticum-caused infection involves an increase of reactive oxygen species (ROS) levels in the vessels, creating the conditions for the scission of polysaccharides and modification of plant cell wall composition. Both the release of rhamnogalacturonan I and the increase in ROS precede colonisation of the vessels by bacteria and occur only in the primary xylem vessels, the same as the subsequent formation of bacterial emboli. Since the appearance of rhamnogalacturonan I and increase in ROS levels do not hamper the bacterial cells and form a basis for the assembly of bacterial emboli, these reactions may be regarded as part of the susceptible response of the plant. Bacterial emboli thus represent the products of host-pathogen integration, since the formation of these structures requires the action of both partners.

[Identification and characterization of non-cultivated forms of enterobacteria Erwinia carotovora in continuously incubated cultures].

AIM: To determine overall number as well as number of viable cells in continuously incubated cultures of E. carotovora by methods of confocal microscopy and quantitative PCR-analysis. MATERIALS AND METHODS: Strain E. carotovora atroseptica SCRI1043 was grown on LB medium to density 2x10(9) CFU/ml. Cells were aggregated by centrifugation and transferred on fresh LB medium, containing alkyloxybenzol, or on the AB medium, which was deficient on phosphorus and carbon. BacLight LIVE/ DEAD kit in combination with confocal laser microscopy as well as quantitative PCR were used for the determination of the number of viable cells. RESULTS: Total number and number of viable cells in cultures on AB medium was high (10() - 10(9) and 10(7) - 10(8) cells/ml respectively) up to 3 - 5 months of cultivation. Though, number of cultivated cells significantly decreased in all variants of the experiment. Number of viable cells in such cultures was several orders greater than genomic copies detected by PCR. Efficacy of DNA amplification increased after dialysis and deproteinization of samples. CONCLUSION: Loss of cultivation ability when number of viable bacteria is high points to possible switch of E. carotovora cells in non-cultivated state under unfavourable conditions. We assume that it is accompanied by formation of low-molecular components and DNA-bound proteins in cells, which inhibit PCR.

FTIR-spectroscopic studies of the fine structure of nitrocellulose treated by Desulfovibrio desulfuricans.

Most studies have concluded that nitrocellulose (NC) with high degree of nitrogen content is resistant to biodegradation. Our results demonstrated that NC (>11%N) does undergo biotransformation in the presence of sulfate-reducing bacteria Desulfovibrio desulfuricans 1388. FTIR analyses indicated that the substitution of nitro groups for OH(-) groups took place. The spectrum of precipitate obtained after acetone extraction of NC resembled mainly the spectrum of native cellulose. Thus the synthetic unbiodegradable polymer was transformed to the natural compound accessible for microorganisms.

Changes in the nitrocellulose molecule induced by sulfate-reducing bacteria Desulfovibrio desulfuricans 1,388. The enzymes participating in this process.

The appearance of unsubstituted glucopyranose residues in nitrocellulose (NC) induced by Desulfovibrio desulfuricans was established by (13)C-NMR spectroscopy. After contact with bacterial cells, the degree of substitution by nitro groups in NC decreased from 2.59 to 2.40. The bacteria possess intra- and extracellular nitroesterase activities, which are responsible for denitration of the polymer. The presence of NC in the growth medium influences the extracellular nitroesterase activity. It is shown that inhibition of enzymatic activity in the presence of NC is caused by appearance of nitrates in the culture medium. Nitrate and nitrite reductases of dissimilatory type reduce nitrates. The data suggest consideration of bacteria belonging to the Desulfovibrio genus as the initial agent in utilization of an unnatural polymer--nitrocellulose--in a microbial consortium.

Biotechnological potential of sulfate-reducing bacteria for transformation of nitrocellulose.

The biotransformation of NC by Desulfovibrio sp. was studied. The mass of NC was decreased by 4.9-9.3%. The rate of NC transformation was between 46 and 73 mg NC per mg of bacterial protein in 10 days. Moreover, N content (%N) in the remaining NC was reduced by 2-12%. The inhibitory effect of NC was clearly expressed when the growth of D. desulfuricans 1388 in lactate/sulfate medium was initiated. The growth rate of bacteria was 1.5-fold greater when NC was not added (0.074 and 0.05 h(-1) respectively). The transformation of NC by D. desulfuricans was accompanied by the appearance of nitrate in the culture liquid, the amount of which reached the peak by the 8th day.

[The incidence of detecting antibodies to the hepatitis C virus in children in specialized children's institutions]. / Chastota vyiavleniia antitel k virusu gepatita C u detei spetsializirovannykh detskikh uchrezhdenii.

Marked differences in the distribution of markers of hepatitis C and B among children in closed children's institutions was established. The frequency of detection of anti-C100-3 in children varied from O in St. Petersburg to 29.4% in Nalchik. A high rate of infection in children is primarily associated with a low level of medico-sanitary service. The results indicate the advisability of specific prophylaxis of viral hepatitis C in specialized children's institutions.