Lactic acid bacteria biofilms and their ability to mitigate Escherichia coli O157:H7 surface colonization

Abstract

Lactic acid bacteria (LAB) exert antagonistic activities against diversemicroorganisms, including pathogens. In this work, we aimed to investigatethe ability of LAB strains isolated from food to produce biofilms and to inhibitgrowth and surface colonization of Enterohaemorrhagic Escherichia coli(EHEC) O157:H7 at 10°C. The ability of 100 isolated LAB to inhibit EHECO157:H7 NCTC12900 growth was evaluated in agar diffusion assays. ThirtysevenLAB strains showed strong growth inhibitory effect on EHEC. Thehighest inhibitory activities corresponded to LAB strains belonging toLactiplantibacillus plantarum, Pediococcus acidilactici and Pediococcuspentosaceus species. Eighteen out of the 37 strains that showed growthinhibitory effects on EHEC also had the ability to form biofilms on polystyrenesurfaces at 10°C and 30°C. Pre-established biofilms on polystyrene of four ofthese LAB strains were able to reduce significantly surface colonization byEHEC at low temperature (10°C). Among these four strains, Lact. plantarumCRL 1075 not only inhibited EHEC but also was able to grow in the presenceof the enteric pathogen. Therefore, this strain proved to be a good candidatefor further technological studies oriented to its application in food-processingenvironments to mitigate undesirable surface contaminations of E. coli.