Heavy metal pollution is one of the most important environmental issues of today. Bioremediation by microorganisms is one of technologies extensively used for pollution treatment. In this study, we investigated the heavy metal resistance and zinc bioaccumulation by microbial consortium isolated from nickel sludge disposal site near Sereď (Slovakia). The composition of consortium was analyzed based on MALDI-TOF MS of cultivable bacteria and we have shown that the consortium was dominated by bacteria of genus Arthrobacter. While consortium showed very good growth in the zinc presence, it was able to remove only 15 % of zinc from liquid media. Selected members of consortia have shown lower growth rates in the zinc presence but selected isolates have shown much higher bioaccumulation abilities compared to whole consortium (up to 90 % of zinc removal for NH1 strain). Bioremediation is frequently accelerated through injection of native microbiota into a contaminated area. Based on data obtained in this study, we can conclude that careful selection of native microbiota could lead to the identification of bacteria with increased bioaccumulation abilities.
Multiple metallotolerant bacterial strains were isolated from soil and drainage water samples collected from three industrially heavy metals polluted areas in Slovakia. Obtained bacterial isolates were identified using MALDI-TOF mass spectrometry and bacterial isolates that belonged to the Acinetobacter genus were subjected for the further study. A. calcoaceticus was found to be prevalent species among analyzed Acinetobacter spp. strains, followed by A. lwoffii and A. johnsonii. A. calcoaceticus strains exhibited higher minimum inhibitory concentration to Mn, Zn, and Cu cations compared to A. lwoffii and A. johnsonii. On the other hand minimum inhibitory concentration to Co and Ni were identical in all Acinetobacter spp. isolates. Genetic analyses demonstrated multiple plasmids presence in A. lwoffii and A. johnsonii but not in A. calcoaceticus. Using ERIC-PCR the presence of two different genotypes of A. calcoaceticus was detected in heavy metal polluted environments in Slovakia.
Tatra National Park is considered as the most visited protected area in Slovakia. Striking a balance between the preservation of natural resources and opportunities for public recreation often forces responsible authorities to make compromises between visitation impacts and protection. In this case, the microbial investigation of recreation effects on water and soil in the Tatra National Park were studied.
The study areas were two valleys – Malá Studená, accessible by trail from south with higher human impact and visitation, including mountain huts Téryho and Zamkovského chata and Javorová, accessible from the northern part with a low number of visitors. Soil samples were taken from the main path, 30 cm away from it and water samples from or near the main path in both valleys. The selected colonies, after the cultivation on TSA medium were also analysed according to the dry and semi-extraction procedure of MALDI–TOF method. Most of the obtained strains are endospore forming, psychrotolerant species like Pseudomonas, Bacillus or Paenibacillus away of path, which corresponds with the climate and geographical conditions. But, the relatedness of soil sample strains in both valleys increases with rising altitude, with distance away from path; in contrast, the relatedness of water samples strains in both valleys increases with increasing distance sample areas from chalet and frequent visitors’ places. Water and soil samples were processed for community level physiological profiling using Biolog EcoPlates. The obtained results of carbon source utilization abilities of bacterial communities in both valleys suggested lower diversity in Javorová Valley, which corresponds probably with less visitor intensity, with less anthropogenic impact as well as with less risk of xenobiotics presence in environment.
Waste disposal sites from non-ferrous metal industry constitute environments very hostile for life due to the presence of very specialized abiotic factors (pH, salt concentration, heavy metals content). In our experiments microflora of two waste disposal sites in Slovakia – brown mud disposal site from aluminium production near Ziar nad Hronom and nickel sludge disposal site near Sered - was analyzed for cultivable bacteria. Isolated bacteria were characterized by a combination of classical microbiological approaches and molecular methods and the most of isolated bacteria shown a poly-extremotolerant phenotype. The most frequently halotolerant (resistant to the high level of salt concentrations) and alkalitolerant (resistant to the high pH level) bacteria belonging to the Actinobacteria class were detected. The most of bacteria shown very high level of heavy metal resistance e.g. more than 500 μg/ml for Zn2+ or Cu2+. Based on our data, waste disposal sites thus on one side represents an important environmental burden but on other side they are a source of new poly-extremotolerant bacterial strains and species possibly used in many biotechnology and bioremediation applications.