Microplastics potential role as a carrier for protozoan, bacteria and SARS-CoV-2

This study investigated the presence of Protozoa, Bacteria, and SARS-CoV-2 RNAs on the surface of microplastics (MPs) collected from a wastewater treatment plant and the Qara-sou river in Kermanshah, Iran. Protozoa presence was examined using light microscopy, with their characterization based on morphology and size. Common bacteria and COVID-19 virus RNAs were identified using molecular detection kits and real-time quantitative polymerase chain reaction (RT-qPCR). Coliform bacteria were assessed using MTFs and IMVIC tests. The analysis revealed a variety of plastic polymers in the samples, including polyethylene, polypropylene, nylon, polystyrene, and PET. Initially, only Pseudomonas was confirmed among the pathogenic bacteria. The highest amount of extracted DNA belonged to Bacillus cereus. All samples showed coliform contamination exceeding 1100 MPN per 100 mL, with positive results for Thermotolerant coliforms. Other bacteria such as Klebsiella pneumoniae, Serratia, and Enterobacter were also detected and confirmed. The predominant microplastic types in the wastewater acted as carriers for virus RNA, with only virus RNA being identified. Additionally, Euglena was the most abundant protozoan in the microplastic biofilm, followed by a large number of Paramecium. Stalked ciliates like Vorticella and Carchesium were present in significant numbers, along with a few Tardigrades (water bears) and Euplotes, and one sample containing an insect larva. SEM images revealed the presence of bacteria, actinomycetes, diatoms, and other protozoa in the biofilm structures. The results suggest that microplastics can serve as platforms for biofilm growth and habitats for microorganisms. Also see: https://micro2024.sciencesconf.org/544602/document