Metal Resistance of Microorganisms as a Crucial Factor for Their Homeostasis and Sustainable Environment

Heavy metals are prevalent environmental components, but when their concentrations exceed critical thresholds, they pose environmental hazards, disrupting the sustainability of ecosystems. Microorganisms are among the first to encounter the toxic effects of metals. Therefore, it is crucial to understand both the levels and mechanisms of their resistance to maintain their homeostasis under the pressure of extreme factors as well as contribute to increasing the sustainability of ecosystems. The aim of the study was to examine two soil bacterial strains, Brevundimonas vesicularis USM1 and Pseudomonas putida USM4, to assess their resistance levels to toxic metals and to identify the mechanisms behind this resistance. For this purpose, microbiological, statistical, and bioinformatics methods were used. The comparative analysis of the two strains revealed that P. putida USM4 exhibited greater resistance to Cr(VI), Co(II), Cu(II), Ni(II), and Fe(III) compared to B. vesicularis USM1. This was confirmed by the metal concentrations at which the strains could survive, their growth dynamics, and the genetically based resistance mechanisms. These findings enhance our understanding of microbial metal resistance and contribute to the advancement of microbial-based environmental biotechnologies.