Micael Siegert Schimmunecha, Carolina Deuttner Neumann Barrosoa, Anderson Ferreira Da Cunhab, Marcelo Mendes Brandãoc, Daniel Cruzd , Karina Ishidad, Marcelo Beltrão Molentoa,*
a Laboratory of Veterinary Clinical Parasitology, Department of Veterinary Medicine, Federal University of Paraná, Curitiba, PR, Brazil.
b Laboratory of Biochemistry and Applied Genetics, Department of Genetics and Evolution, Federal University of São Carlos, São Carlos, Brazil.
c Laboratory of Integrative and Systemic Biology, Center of Molecular Biology and Genetic Engineering, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.
d World Animal Protection. São Paulo, SP, Brazil.
Braz. arch. biol. technol. 69 • 2026 • https://doi.org/10.1590/1678-4324-2026250900
Urbanization and intensive animal farming generate large volumes of waste that introduce microbial contaminants into aquatic ecosystems, increasing the risk of pathogen dissemination. We analyzed 16S rRNA-based microbial community profiles from water samples collected upstream and downstream of pig farms and urban areas in southern Brazil including Itambaracá (P1, P3), Chapecó (P2, P4), Curitiba (P5) and Joinville (P6). Proteobacteria dominated most samples, with Gammaproteobacteria enriched near pig farming sites. Urban-impacted waters showed reduced microbial diversity and clear taxonomic shifts consistent with wastewater influence. Notably, pathogenic bacteria of public health concern, including Escherichia coli O157:H7, Shigella flexneri 2a, and Pseudomonas aeruginosa, were detected in areas affected by livestock production and urban effluent discharge. These findings demonstrate that animal production systems and urban wastewater may act as interconnected sources of environmental contamination, reshaping aquatic microbiomes and introducing clinically relevant pathogens into natural waters. This convergence highlights the need for integrated monitoring and management strategies to protect ecosystem integrity and reduce human health risks.