Publication year: 2011Source: Water Research, In Press, Accepted Manuscript, Available online 22 August 2011Vania, Figueira , Ivone, Vaz-Moreira , Marcia, Silva , Celia M., ManaiaThe taxonomic diversity and antibiotic resistance phenotypes of aeromonads were examined in samples from drinking and waste water treatment plants (surface, ground and disinfected water in a drinking water treatment plant, and raw and treated waste water) and tap water. Bacteria identification and intra-species variation were determined based on the analysis of the 16S rRNA, gyrB and cpn60 gene sequences. Resistance phenotypes were determined using the disc diffusion method.Aeromonas veronii prevailed in raw surface water, A. hydrophyla in ozonated water, and A. media and A. puntacta in waste water. No aeromonads were detected in ground water, after the chlorination tank... Highlights: ► urban water cycle. ► No strong evidences for clonal dissemination of antimicrobial resistance. ► Water ozonation imposed a bottleneck on species diversity. ► A. media and A. punctata were important reservoirs of quinolone resistance. ► Water aeromonads could be significantly reduced by water chlorination.