The anthropogenic pressure on ecosystems may contribute to the spread of antibiotic resistance among bacteria in natural conditions. Due to this, the aim of this work was to study the impact of specific biocides, antibiotics, pesticides and heavy metals on the emergence of rifampicin resistant mutants of Pseudomonas putida. To assess the impact of toxic substances on the emergence of rifampicin-resistant mutants the studied substances and rifampicin in the final concentration of 100 ?g/ml were added into nutrient medium before plating.