Caracterização físico-química e microbiológica do rio Camarajipe e perspectivas biotecnológicas de biorremediação

Abstract

Introduction: Surface water contamination is a global issue largely driven by the eutrophication of rivers due to anthropogenic activities. A significant contribution to this scenario stems from the discharge of effluents and pharmaceutical and industrial ingredients, such as antimicrobials and recalcitrant compounds, which promote the emergence of multidrug-resistant (MDR) bacteria and infectious diseases. This reality constitutes a global public health concern; however, from a One Health perspective, it is possible to mitigate and remediate both chemical and biological contaminants. Objectives: To characterize the physicochemical and microbiological (quantitative and qualitative) parameters of water samples from the Camarajipe River in Salvador, Bahia, and to propose a sustainable solution for the bioremediation of recalcitrant compounds found in the river. Materials and Methods: To guide the research, a systematic review was conducted to investigate the antimicrobial resistance profile of bacteria in treated effluents from wastewater treatment plants in Latin America, following PRISMA guidelines and the PICO strategy. Over the course of seven sampling events, water samples were collected from four distinct sites along the Camarajipe River. These samples were analyzed for physicochemical parameters and processed for total and thermotolerant coliform counts. Furthermore, carbapenem-resistant Gram-negative bacilli (GNB) were isolated using selective culture media and identified via MALDI-TOF. Subsequently, bacterial susceptibility testing was performed on the isolates obtained. Additionally, experiments were conducted to develop a biological filter aimed at degrading recalcitrant compounds. Results: The systematic review revealed that the majority of wastewater treatment plants fail to eliminate MDR bacterial strains from treated effluents (19/20), as demonstrated through both physicochemical analyses and bacterial isolation. In the experimental study, physicochemical and microbiological analyses indicated that the Camarajipe River is eutrophic and functions as a reservoir for MDR GNB (43/47), which were found across all sampling sites. Among the isolates, strains of Pseudomonas spp. (31/47) and Klebsiella pneumoniae (11/47) were the most prevalent. As a bioremediation strategy, the constructed biological filter showed promising results in reducing Remazol Brilliant Blue, a recalcitrant compound associated with textile industry effluent contamination. Final Considerations: The Camarajipe River exhibits signs of eutrophication and acts as a vector for both chemical and biological contaminants, contributing to the spread of MDR GNB strains. As a potential tool to mitigate chemical pollution, the developed biological filter demonstrates promise; however, further testing is required to validate the prototype, including saturation and absorption capacity regeneration assays for the activated carbon.