Resistance of Actinobacteria of the Genus Gordonia to Heavy Metals
Tishchenko, Artyom (1); Bakieva, Elmira (2); Litvinenko, Ludmila (3); Ivshina, Irina (1,3)
1: PSU, Russian Federation; 2: PSTU, Russian Federation; 3: IEGM UB RAS, Russian Federation
Application of environmentally friendly methods for bioremediation of soils and water bodies contaminated with heavy metals (HMs) is a hot issue. Due to the increased volumes of household and industrial waste, the wastewater treatment plants suffer from high loads of influents heavily contaminated with these pollutants. In this regard, the increased research interest is focused on actinobacteria that use natural and anthropogenic hydrocarbons as carbon sources, as well as those able to produce active biosurfactant complexes that contribute to mobilization and desorption of HM ions. The purpose of this work is to analyze the degree of resistance of alkanotrophic actinobacteria to HMs.
The working collection included 98 strains of actinobacteria from the Regional Specialized Collection of Alkanotrophic Microorganisms (www.iegmcol.ru) representing the species Gordonia alkanivorans (2), G. amicalis (8), G. rubripertincta (59), and G. terrae (29). Gordoniae were pre-grown in the meat-peptone agar for 48 hours. The following salts were used in this work: CuSO4x5H2O, (CH3COO)2Cdx2H2O, K2CrO4, (NH4)6Mo7O24x4H2O, NiSO4x7H2O, Pb(NO3)2, ZnSO4x7H2O in concentrations ranging from 0.08 to 80.00 mM. The degree of actinobacterial resistance to HMs was evaluated based on the minimum inhibitory concentrations (MICs) determined by the microwell method. The viability of bacterial cells was determined using 0.2 % aqueous solution of iodonitrotetrazolium chloride. The experiments were carried out in quadruplicates.
According to our data, all cultures retained their ability to grow in the presence of HM ions. At the same time, MIC values varied in the range from 0.08 to 40.00 mM. HMs according to their toxic effects on the studied cultures of Gordonia are distributed in the row: Cd2+ > MoO42- > Zn2+ > Cu2+ > Ni2+ > CrO42- > Pb2+, where cadmium is the most toxic, and lead is the less toxic. It was established that, the strains of different Gordonia species differed by 2‒125 times according to their degree of resistance to HMs. Apparently, the intraspecific heterogeneity in resistance to HM ions is associated with the ecological confinements of bacterial strains. Gordonia spp. used in the study are distributed in the row: G. amicalis> G. alkanivorans> G. terrae> G. rubripertincta.
The selected collection strains of G. alkanivorans IEGM 748, G. amicalis IEGM 1266, 1274, G. rubripertincta IEGM 126, 733,and G. terrae IEGM 149, 735 had the highest degrees of MICs (from 0.16 to 40.00 mm).
The study was carried out under the state assignment (01201353247) and the Integrated program 18-4-8-21.