Relação dos sistemas de reparo de DNA em Escherichia coli K-12 com resistência a antibióticos, características adesivas e formação de biofilme

• Autor(a) principal: Costa, Suelen Bozzi
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14394
• topic: E. coli K-12; Antimicrobianos; Aderência; Filamentação e biofilmes; E. coli K-12; Antimicrobials; Adherence; Filamentation and biofilms; CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA::MICROBIOLOGIA APLICADA

The reactive oxygen species (ROS) are generated during normal cellular metabolism and can produce several oxidative damage in the DNA, such as lesion nitrogen bases or apurinic/apirimidinic (AP) sites. These lesions may lead to the accumulation of mutations site, if such damages are not repaired. However, the bacteria have several mechanisms of protection against the ROS which play an important role in the maintenance of physiology. The objective of this study was to assess whether enzymatic systems, such as base excision repair (BER), SoxRS and SOS systems are capable to interfere with bacterial response to environmental signals such as susceptibility to antibiotics, and microbial adherence to biotic (HEp-2 cells) and abiotic surfaces (biofilm formation). The mutant strains used in this study were derivatives of Escherichia coli K-12. It was observed that the sole mutant presenting differences in antimicrobial susceptibility in relation to the parental wild type strain (AB1157) was BW9091 (xthA- -deficient in exonuclease III). Nevertheless, 11 strains with deficiency in different protective mechanisms to oxidative stress, presented differences in adherence patterns to HEp-2 cells, demonstrating an aggregative-like adherence in relation to the parental strain AB1157 (without a typical adherence pattern). Presence of mannose (a carbohydrate capable to block type I-mediated fimbriae adherence) was capable to interfere with both quantitative adherence and filamentation of bacterial cells. Filamentation is an important SOS response observed in genome repair during bacterial cell division. Furthermore, with respect to the formation of biofilms, 8 strains showed a strong biofilm formation where this response was not accompanied by increased in intensity of filamentation. Our results suggest the involvement of oxidative stress in the definition of parameters such as sensitivity to antimicrobials, pattern and intensity of adhesion, and filamentous formation of biofilms in the samples of E. coli K-12 assessed in this study. We suggest that adherence generates oxidative stress causing damage to the DNA, which leads to induction of the SOS system resulting in the filamentation.