Journal of Water and Health (Oct 2023)
First report of free-living amoebae in sewage treatment plants in Porto Alegre, southern Brazil
Abstract
Free-living amoebae (FLA) are amphizoic protozoans with a cosmopolitan distribution. Some strains of species are associated with infections in humans. They feed on microorganisms by phagocytosis; however, some of these can become endocytobionts by resisting this process and taking shelter inside the amoeba. The whole world is experiencing increasing shortage of water, and sewage is being reused, so the study of this environment is important in public health context. The objective of this work was to identify FLA present in sewage treatment plants in Porto Alegre, Brazil. About 1 L samples were collected from eight stations (raw and treated sewage) in January, February, July, and August 2022. The samples were sown in monoxenic culture, and the isolated amoebae were subjected to morphological and molecular identification. Polymerase chain reaction results indicated the presence of the genus Acanthamoeba in 100% of the samples. Gene sequencing showed the presence of Acanthamoeba lenticulata and Acanthamoeba polyphaga - T5 and T4 genotypes - respectively, which are related to pathogenicity. The environment where the sewage is released can be used in recreational activities, exposing individuals to potential interactions with these amoebae and their potential endocytobionts, which may pose risks to public health. HIGHLIGHTS Free-living amoebae were isolated for the first time in sewage treatment plants (STPs) in Brazil.; In the STPs of Porto Alegre, RS, Brazil, only the genus Acanthamoeba was isolated, and genotypes associated with pathogenicity (T4 and T5) were identified.; The Guaíba lake and the Gravataí river receive the city's sewage and, consequently, can disperse Acanthamoeba spp.; Further research on the prevalence and identification of free-living amoebae in sewage is still needed in Brazil.;
Keywords
