Utilização da coluna de Winogradsky para demonstração do efeito de antibióticos de uso comum na microbiota do Rio Alegria - PR: uma abordagem experimental

Abstract

The indiscriminate use of antibiotics has caused environmental impacts, affecting aquatic microbiota and promoting bacterial resistance. This study investigated the effects of ciprofloxacin, chloramphenicol, sulfamethoxazole, sulfaclorperidazine, and tetracycline on the microbiota of the Alegria River (Medianeira, PR) using the Winogradsky Column. The columns were prepared with water and sediment from the river, containing 500 µL of each antibiotic, along with carbon and sulfur sources. The experiment lasted three months. Analyses included observations of microbial communities, biweekly pH measurements, phytotoxicity assays with lettuce seeds, and heterotrophic bacterial counts on PCA medium. The results indicated that tetracycline favored sulfate-reducing and anaerobic photosynthetic bacteria. Chloramphenicol and ciprofloxacin stimulated some bacteria but reduced overall growth. Sulfamethoxazole inhibited photosynthetic bacteria, while sulfaclorperidazine favored green sulfur bacteria. The pH ranged between 5 and 6 in all treatments. Phytotoxicity tests showed that chloramphenicol was initially toxic, with a germination index (GI) of 26%, but later stimulated germination (GI 200%), while sulfamethoxazole was toxic in all analyses (GI 44%). Tetracycline stimulated germination in the final analysis (GI 250%). Microbial counts indicated that tetracycline and ciprofloxacin favored resistant populations, whereas the other antibiotics reduced bacterial density. The results highlight that antibiotics influence microbial succession, alter water quality, and impact biota, reinforcing the need for environmental monitoring and studies on the long-term effects of these compounds.