Resistance to Heavy Metals of Actinobacteria Isolated From the Biological Fouling of Shellfish and Mussels of the Odesa Gulf of the Black Sea

Abstract

SummaryEnvironmental pollution with heavy metals/metalloids is one of the most important environmental problems, which leads to the development of bioremediation strategies and the search for biomarkers to assess its condition. Aim. To determine the sensitivity to heavy metals of actinobacteria isolated from the biological fouling of natural shell rock and mussels of the Odesa gulf of the Black Sea. Methods. Thirty-four strains of actinobacteria isolated from fouling of shell rock and mussels of the Odesa gulf were used in the investigation. The sensitivity of the studied bacteria to heavy metal cations was determined on starch-casein agar by the disk diffusion method. Discs impregnated with salts solutions of Cu2+, Co2+, Ni2+, Cd2+, Zn2+ in concentrations of 0.001 mol/l, 0.01 mol/l, 0.05 mol/l, 0.1 mol/l, 0.5 mol/l and 1.0 mol/l were used. Results. The investigated actinobacteria showed variable sensitivity to heavy metals, which depended on the source of isolation, strain, type of metal and its concentration. All tested bacteria were most sensitive to Cd2+ (MIC was 0.001 mol/l), the most resistant to Zn2+ (MIC was higher than 1.0 mol/l for the vast majority of bacteria). At concentrations lower than the MIC, zinc stimulated the formation of aerial mycelium of almost all strains, and pigment formation increased in some of them. The sensitivity to heavy metals of actinobacteria isolated from shellfish decreased in the following sequence: Cd2+>Cu2+>Co2+>Ni2+>Zn2+, and in actinobacteria isolated from mussels – Cd2+>Cu2+>Ni2+>Co2+>Zn2+. Conclusions. Actinobacteria isolated from mussels are more sensitive to cadmium, cuprum, cobalt, nickel and zinc, compared with actinobacteria from shell rock. All studied strains were highly sensitive to Cd2+ (MIC Cd2+ for almost all strains was 0.001 mol/l) and resistant to Zn2+ in the concentration range of 0.001 mol/l – 0.5 mol/l.