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Inhibitory effect of supernatants from a competitive exclusion culture over growth of some intestinal pathogens

Aguilar-Rivera, C., Hume, M. E., Klotz-Ceberio, B. F.
Revista Mexicana de Ingenieria Quimica 2016 v.15 no.2 pp. 379-389
Salmonella Enteritidis, Shigella sonnei, animal pathogenic bacteria, antagonism, bacterial communities, bacteriocins, competitive exclusion, enteropathogenic Escherichia coli, enzyme activity, feces, food industry, gastrointestinal system, growth curves, humans, intestinal microorganisms, models, peptidase K, pharmaceutical industry, public health, trypsin
Competitive exclusion cultures (CEC), which use whole bacterial communities derived directly from the gastrointestinal tract, have been effective in controlling pathogens in animals, but their application in humans have not been widely studied. In this work, the inhibitory effect of supernatants obtained from a CEC developed from fecal samples of healthy individuals was examined on the growth of intestinal pathogens which are of public health significance. The Baranyi Model was adjusted (R-square > 0.947) to growth curves of Shigella sonnei (SF1), E. coli EPEC (EC6), and Salmonella Enteritidis (SE3) treated with supernatants in order to estimate kinetic parameters. Growth rates and pathogen concentrations were significantly reduced by the action of supernatants in 89.89% and 86.80%, respectively, for the most sensitive bacteria (SF1) and 23.21% and 36.86% for the most resistant (SE3). A growth delay of more than 14 hours was presented by SF1 and EC6 with the treatments. Thermal and enzymatic (proteinase K and trypsin) sensitivity of supernatants indicates that antagonism was mediated by bacteriocin-like substances. The CEC developed has biotechnological potential for the production of antimicrobial substances of interest in the food and pharmaceutical industries.