Authors: Sukhodub L.B., Yudin I.P., Gushilik B.I., Pokhil S.V., Kazmirchuk V.V.
Under the influence of the environment pathogenic bacteria may become viable, but nonculturable characterized by the inability of microorganisms to grow in vitro. Indicator assessing the viability of microorganisms enough depends on the characteristics of the method used and the subjective factor, so it becomes more urgent precise quantitative analysis of viable bacteria in the material. The objective of this study was to develop methods for determining the status nonculturable bacteria E. coli, S. sonnei, S. flexneri, S. enteritidis, caused by the action of a biocide - sodium hypochlorite by fluorescence microscopy on membrane filters using fluorochromes rhodamine 123 to identify viable cells and propidium iodide, as an indicator of non-living cells. Research has shown that even after 300 seconds in the biocide action of 1 mg/l of active chlorine still possible to identify viable microorganisms, while under the standard method for seeding onto solid medium the culturability E. coli and S. enteritidis was observed only after 10 second action said biocide concentration, S. sonnei and S. flexneri under these conditions did not show the growth. All tested microorganisms cultured at 20°C, proved to be more resistant to biocide than cultured at 37 °C.
Keywords: enterobacteria, nonculturable state, method of fluorescence microscopy on membrane filters.