Biofilm formation by environmental bacteria

Abstract

The majority of bacteria in the environment live associated with surfaces, in so called biofilms. Bacterial cells embedded in a biofilm can better withstand environmental stress, such as nutrient deprivation, unphysiological temperatures and pH changes. Within the biofilm they become more resistant to detachment, oxygen radicals, disinfectants, and antibiotics than the individual planktonic cells. In this chapter, the current status of biofilm research is summarized, with focus on the mechanims involved in formation of biofilms, characteristics of bacteria living in biofilms, e.g. the production of extracelluar polymeric substances (EPS) and the intercellular communication via quorum sensing. Detrimental and beneficial effects of microbial biofilms are described, as well as their application in modern biotechnology. An overview about state of the art techniques to analyse complex biofilms is given, as well as a summary on existing and emerging biofilm inhibitors. We developed a continuous upflow biofilm reactor system where mixed species environmental biofilms can form attached to glass beads. Studies on these biofilms by lectin-binding analysis and fluorescence microscopy are described. Experimental systems developed to visualize biofilms by fluorescent labels using confocal laser scanning microscopy (CLSM) and the current strategies in removing or controlling the biofilm are dicussed. The chapter ends with perspectives on the development of new emerging biofilm inhibitors and with an outlook on new promising techniques that will enable analysis of the composition as well as the structure of biofilms in even more detail.