Influência de agentes antimicrobianos e ambientais nas comunidades bacterianas e nos níveis de resistência a antibióticos numa estação de tratamento de águas residuais

Abstract

The variation of the bacterial community structure in a municipal activated sludge wastewater treatment plant (WWTP) was assessed before and after treatment, through the method of denaturing gradient gel electrophoresis (DGGE). The DGGE community patterns, corresponding to fourteen sampling campaigns over different seasons, were analysed as a function of different biotic and abiotic environmental variables through multivariate statistical analysis. Based on the analysis of the nucleotide sequences of the excised DGGE bands, it was possible to conclude that the predominant populations were Proteobacteria of the classes Beta-, Epsilon- and Gamma-, and Bacteroidetes. A principal component analysis (PCA) based on DGGE patterns showed that the composition and structure of bacterial communities varied over time and differently for each type of wastewater (raw or treated). The canonical correspondence analysis (CCA) of the DGGE patterns versus environmental variables suggested a significant influence of some factors, such as temperature and the relative humidity, in the treated effluent. The presence of some chemical compounds such as tetracyclines, and culturable coliforms resistant to ciprofloxacin or to sulfamethoxazole showed also to have a relationship with the structure of the community. According to this study, the bacterial community of the treated effluent is influenced by culturable antibiotic resistant populations, the presence of antimicrobial agents and the physicochemical conditions. It is possible to conclude that the bacterial community may suffer rearrangements throughout the wastewater treatment, eventually leading to the development of antibiotic resistance in the environment.

Date of Award	2012
Original language	Portuguese
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Célia Manaia (Supervisor) & Olga C. Nunes (Supervisor)