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COMPLEX RESEARCH OF E.coli VITAL ACTIVITY DYNAMICS IN PRESENCE OF TRANSITION METAL IONS

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Subject of Research.The paper presents the study of the effect of the most stable ionic forms of the fourth period Periodic table transition metals with different concentrations on the vital activity of Еscherichia coli. Method. The research was carried out using a complex microbiotest system, which provides for instrumental recording of changes in the intensity of elastic light scattering at 520 nm(Iod), optical density at 300 nm (Auv), pH and the redox potential (E)of samples containing initially the same number of viable test microorganisms incubated in the presence and absence of various concentrations of the test substances during the predetermined time, at given temperature and in liquid nutrient medium of defined composition. Main Results. It is shown, that the most stable ionic forms of the fourth period transition metals can be arranged in the following row according to the decrement of their antimicrobial activity: Cu2+ > Ni2+ > Mn2+ > Cr3+ > Co2+ > Fe3+ > Zn2+. We have carried out a study of fine dynamics of the vital activity of test microorganisms in the presence of the mentioned metal ions. The study has demonstrated, that the maximum growth rate of E.coli (characterized by ΔIod/Δτvalues) in all cases was reached earlier than the maximum rate of change in the metabolic activity of these microorganisms (characterized by ΔE/Δτvalues), and also that in the initial incubation period ΔE/Δτchanged non-monotonically with time as a result of E.coli life activity (it probably has reflected the metabolic processes of E.coli adaptation to the presence of excess metal ions in the test medium). Practical Relevance. The results of this study can be applied in the development of various methods for assessment of the environment ecological state, as well as regulation of the vital activity of microorganisms involved in various biotechnological processes (as producers, biodegradants of various products and materials, etc.), causing various infectious diseases, being part of the beneficial microflora of various water bodies, soils and multicellular living organisms.

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