Chromium bioremediation potential of <i>Exiguobacterium acetylicum—</i> a bacterium isolated from the rhizosphere of <i>H</i> . <i>grumosa</i>

Environmental contamination with hazardous compounds like chromium (Cr) poses significant risks to ecosystems and human health. This study investigates the bioremediation potential of rhizobacteria Exiguobacterium acetylicum isolated from the roots of the aquatic macrophyte Hymenachne grumosa, collected from Santa Barbara Stream, in Southern Brazil. Cr-resistant bacteria from the plant were isolated, characterized, and tested for their capacity to remove Cr under different environmental conditions. The selected strain demonstrated robust Cr removal efficiency, achieving up to 50% removal within 24 hours at 30°C and pH 7, with an initial Cr concentration of 50 mg L-1. The bacterium’s removal capacity improved proportionally with increasing Cr concentrations, showing its adaptability to varying contamination levels, reaching 50% removal in the 75 mg L-1. Furthermore, optimal removal conditions were identified, including temperature (35–40°C) and pH (6–7), highlighting the influence of environmental parameters on bioremediation outcomes. These findings underscore the importance of rhizobacteria associated with aquatic macrophytes in natural attenuation and their potential application in treating Cr-contaminated environments. Future research focusing on bacterial consortia and multi-contaminant systems could further enhance bioremediation strategies, contributing to sustainable solutions for industrial wastewater management and environmental restoration.