Physiological aspects of metal resistance in Pseudomonas bacteria isolated from sediments of Ostrava Lagoons, Czech Republic

摘要

Bacteria with verified toxic-metal-resistance were isolated from the environments with increased metal concentrations, especially from localities contaminated by mining, industrial or agricultural activities. The microbial diversity of sites with a high proportion of metals is characterized by the occurrence of specifically adapted microorganisms; their identification and subsequent accurate genotypic and phenotypic characteristics are a prerequisite for further practical applications, especially in bioremediation processes. The paper examines and compares physiological properties for tolerance to the presence of toxic metals in bacterial species from a single taxonomic genus of Pseudomonas. It compares 8 newly isolated-strains originating from anthropogenic sediments on the locality Ostrava Lagoons (Czech Republic), that is an area with significant pollution. The Ostrava Lagoons are full of crude oil sludge gathered throughout the whole 20~(th) century in Ostrava. The sludge predominantly comes from the local chemical plant Ostramo, dealing with disposal of waste left from crude oil processing. Despite the fact its operation was terminated in 1996, the Ostrava Lagoons are considered one of the most severe environmental loads in the Czech Republic as approximately 200,000 tons of contaminated slurries had been disposed there. In addition to the high content of organic pollutants, contaminated soils contain also other toxic metal elements (As, Cd, Cu, Hg, Ni, Pb). Isolates which showed the highest metal resistance was chosen for further identification by 16S rDNA sequence analysis. The 16S rDNA from the extracted DNA was amplified by PCR using 27F (5'-AGAGTTTGATCCTGGCTCAG-3') and 1492R (5'-ACGGCTACCTTGTTACGACTT-3') primers, for an exact biochemical properties of strains, the method of standard biotypization applying a BiologTM MicroStation system was used. The resistance of the bacterial strains was evaluated on the grounds of maximum tolerance concentration (MTC) representing the top metal concentration which does not demonstrate a physiological effect on the growth of the bacterial strain; higher values represents the metal concentration with a lethal effect on the growth of the bacterial strain. The experimental results corroborate high metal tolerance in the bacterial strains originating from localities rich in heavy metals, among the decisive factors for tolerance there is high bacteria's adaptation capacity reflected by the extensive species diversity of the Pseudomonas bacterial genus.