Protective biofilms using lactic acid bacteria

Abstract

Most bacteria present in natural or domesticated settings usually grow adhered to surface-liquid or liquid-air interfaces and are embedded in a self-produced extracellular polymeric matrix thus forming what is termed biofilms (Costerton et al. 1999). This bacterial way of life may pose a serious sanitary problem, especially in which concerns pathogenic bacteria that, when present in biofilms, exhibit an increased tolerance to most types of biocides used for cleaning and decontamination (Caballero N. et al, 2012). In contrast, biofilms formed by "friendly" lactic acid bacteria (LAB), present in foods, agricultural products or in the gastrointestinal tract of mammals and used as starters in food manufacturing, may offer an extremely promising means to counteract the establishment of pathogen biofilms. According to their properties, these potent so called protective biofilms could prevent the development or displace pathogen biofilms in food chain settings, medical devices or animal breeding buildings (Habimana et al. 2009). This project deals with the investigation of bacterial factors that are likely to affect the activity of protective biofilms towards major Gram+ and Gram- bacterial pathogens. Two bacterial factors namely, bacteriocins and biosurfactants will be study. It is also important to highlight that, while the genome of an organism is essentially constant throughout life, protein expression changes in different stages of the cell cycle, but also in response to external factors. To go further in the understanding of LAB physiology in biofilms, we propose to carry out proteomic studies to determine the differences in protein expression that occur in the different biofilms to be developed within this study.