ZYMOGRAPHIC ANALYSIS OF WATER-SOLUBLE PROTEASES OF VIBRIO CHOLERAE O1 AND О139 SEROGROUPS

Aim. Zymographic analysis of water-soluble proteases of Vibrio cholerae O1 и О139 serogroups. Materials and methods. Bacteria cultivated on a casein-yeast agar (рН 7,6) at 37 ° with during one twenty-four hours and washed off physiological solution. Bacterial mass (by the concentration of 109 cell./ml) was treatment by sterile solution of urea in an eventual concentration 4,5 М. After day's display and determination of sterility of got lysate insoluble in urea material (cell walls) was deleted by high-speed centrifugation. Supernatant liquid was exposed to the dialysis, released from insoluble in water sediment centrifugation and freeze dried out. Protease activity was determined in diffusion test in 1 % agarose gel, containing 0,5 % gelatin or 0,5% casein. The spectrum of proteases was analysed by a substrate electrophoresis in the blocks of 8% polyacrylamide gel, impregnated in the process of polymerization gelatin or casein (in an eventual concentration 0,1 %), in presence the dodecylsulphate of sodium. Results. After differential centrifugation of ureal lysate of cells and dialysis there are mainly intracellular water-soluble proteases in the investigated extracts. Diffusion tests showed that all preparations of the investigated strains of Vibrio cholerae possessed protease activity of different intensity. Changing of substrate in diffusion test from gelatin to the casein resulted in the general diminishing of the registered areas of hydrolysis, specifying that a casein fissions less actively by comparison to gelatin. Substrate electrophoresis showed that proteins, making the spectrum of water-soluble pro teases of Vibrio cholerae are extracted by urea, possessed molecular mass, varying within from less than 30 кйа to more than 120 кDа. Strains distinctions are marked in quantitative and high-quality description of spectrums of soluble proteases. Dependence of description of type of water-soluble proteases is educed on used substrate. At the estimation of spectrums of proteases clear confirmation is got, that on gels are impregnated by gelatin electrophoretic mobility of proteases is higher, than in gels, containing a casein. Conclusion. Substrate electrophoresis of preparations of cell-free lysates of Vibrio cholerae showed the presence of a few water-soluble proteases, quantitative and high-quality interstrain distinctions, dependence of spectrum of active proteases from of used substrate

Assessing the Efciency of Detection of Vibrio cholerae Genetic Determinants Through Waterbody Vibrioflora Monitoring System

Objective of the study was to assess the effectiveness of PCR screening of Vibrio cholerae genetic determinants in samples from surface water reservoirs for optimization of the cholera microbiological monitoring system.Materials and methods. The study was carried out as a part of the vibrioflora monitoring in surface water bodies in Irkutsk city. The study design included: 1) PCR screening of V. cholerae genetic determinants in nutrient-enriched (1 % peptone water) samples from surface water reservoirs during the monitoring period (824 samples); 2) studying of the V. cholerae DNA accumulation dynamics applying PCR assay of the samples from surface water reservoirs during cultivation on the enriched media (16 samples in dynamics); 3) experimental study of the detected V. cholerae concentrations in samples from surface water reservoirs. Species-specifc (hlyA, toxR) and serogroup-specifc (wbeT, wbfR) V. cholerae determinants were indicated in PCR with hybridization-fluorescent and electrophoretic detection.Results and discussion. At the frst stage it was found that the proportion of the positive samples through PCR screening (33.9 %) exceeded the percentage of the positive samples in bacteriological examination (19.3 %) (t=6.6; p<0,01). In the assessment of DNA accumulation dynamics, a decrease in the threshold cycle (Ct) by 1.2–5.2 times was recorded, indicating an increase in the V. cholerae concentration and proving the detection of genetic determinants of viable forms during PCR screening. An extended study of PCR-positive but bacteriologically negative samples made it possible to additionally isolate 4 V. cholerae cultures. However, there were no differences in the sensitivity of PCR screening and bacteriological analysis in the experiment with water samples artifcially contaminated with V. cholerae unlike the analysis of the enriched native samples. It can be determined by the metabolism and adaptation peculiarities of the microorganism in different environmental conditions. The results of the integrated study indicate the epidemiological effectiveness of PCR screening which gives grounds to recommend its application in monitoring studies of vibrioflora from environment after preliminary enrichment on liquid nutrient media in the work of federal, territorial, and regional laboratories