RESUMO
In the present study, siderophore production capacity of various diarrhoeagenic E coli strains was tested on quantitative basis. The collected strains were classified under enteropathogenic E coli, enterotoxigenic E coli and entero-invasive E coli groups by using appropriate techniques. A few reference . enterotoxigenic E coli strains were also included in this study. The confirmation of various properties of enteropathogenic E coli, enterotoxigenic E coli and entero-invasive E coli strains was carried out by standard procedures. Several non-pathogenic E coli strains were also included in the study to assess their siderophore producing capacity. The results presented in the study showed that, the phenolate type of siderophore, that is enterochelin was predominantly produced by majority of these E coli strains. Only 30% of enteropathogenic E coli and 33% of enterotoxigenic E coli strains failed to produce any detectable level of enterochelin. On the other hand, only 50% of enteropathogenic E coli strains and all the entro-invasive E coli (100%) showed the positive aerobactin that is hydroxamate type of siderophore production ability. None of the enterotoxigenic E coli and non-pathogenic strains produced aerobactin.