Biofilms consist of microorganisms attached to a surface and embedded in a matrix with a variable composition. Biofilms can be responsible for (re)contamination of food products and depending of the microorganism cause quality or health issues. The bacteria residing in the biofilm are protected from cleaning and disinfecting agents. In this thesis the biofilms of the food spoilage related bacteria Lactobacillus plantarum were characterised. The major components of the biofilm matrix as well as the possible release mechanism were studied. In nature biofilms are not only composed of one strain, thus the findings of this research provide insights into single, dual and multi-strain planktonic and biofilm growth of selected L. plantarum strains. Even though some strains were not represented as winners they helped cementing the other strains of the biofilm. Information on biofilm matrix composition and correlation to viable cells is of use both in development of strategies to eradicate biofilms and in spoilage risk analysis studies.