ВИКОРИСТАННЯ МЕТОДІВ ДИСПЕРСІЙНОГО І КЛАСТЕРНОГО АНАЛІЗУ ДЛЯ ПОРІВНЯННЯ СТІЙКОСТІ ДО ВАЖКИХ МЕТАЛІВ АЦИДОФІЛЬНИХ ХЕМОЛІТОТРОФНИХ БАКТЕРІЙ, ВИДІЛЕНИХ ІЗ ТЕХНОГЕННОЇ СИРОВИНИ

Abstract

In the present work, the resistance to heavy metals of one reference strain Acidithiobacillus ferrooxidans ATCC 23270 and eight strains of acidophilic chemolithotrophic microorganisms isolated from dump products of the fuel and energy complex of Ukraine of various types was investigated. For the study were used metals that have the property of substituents (Zn 2+ , Ni 2+ , Co 2+ ), metals of the “combined” action (Cu 2+ ), and metals that do not perform biological functions (Cd 2+ , Pb 2+ ), but which are able to form insoluble complexes on/into the cells or interact with nucleic acids. It was established that the impact of metals on the studied strains of acidophilic chemolithotrophic bacteria is ambiguous and does not correspond to the scale of interaction of metals with nitrogenous heterocyclic bases of DNA. The maximum number of strains were resistant to cobalt ions (66.6 % with an MIС value of 0.09 M). about 55.5 % of the strains were resistant to impact of copper, cadmium and zinc ions with indicators of MIC of 0.13, 0.061, and 0.083 M, respectively. A statistic analysis of obtained results of the resistance to heavy metals of acidophilic chemolithotrophic bacteria with used using the methods of dispersion and cluster analyzes in the R 3.4.0 program was carried out. Clustering of the results according to the minimum inhibitory concentrations allowed us to group the studied metals into three clusters: a single (Pb 2+ ), a cluster (Zn 2+ , Ni 2+ , Co 2+ , Cd 2+ ) and subcluster (Cu 2+ ). Also, hierarchical cluster analysis based on the level of resistance of strains allowed us to divide the studied strains into two groups depending on their level of resistance to metals. The strains that were isolated from coal wastes were the most resistant to the studied metals. The active systems of metal transport of studied acidophilic chemolithotrophic bacteria were theoretically predicted based on literature data analysis. The difference in the level of resistance to metals in A. ferrooxidans and A. thiooxidans was partially associated with the use of bivalent iron as an energy source. The heterogeneity of efflux systems response to the action of heavy metals within the group of microorganisms belonging to A. ferrooxidans was shown.