APPLICATION OF MICROPLATE BIOFILM ASSAY AND MICROSCOPY TECHNIQUES TO INVESTIGATE ABILITY OF SOME BACTERIAL STRAINS OF ANIMAL ORIGIN TO FORM BIOFILM

Abstract

The use of some procedures for in vitro investigation of biofilm formation in bacterial species Staphylococcus aureus, Listeria monocytogenes and Pseudomonas aeruginosa isolated from animals is presented in this paper. Biofilms are formed on polystyrene and stainless steel surfaces. On polystyrene surface S. aureus and L. monocytogenes were examined by microplate biofilm assay and light microscopy. Biofilms of L. monocytogenes, S. aureus and P. aeruginosa, formed on stainless steel surface, were examined by scanning electron microscopy. The application of these methods can help distinguish between the bacteria isolates that don’t form and the one that form biofilm. Microplate biofilm assay proved to be a simple method suitable for examining a large number of isolates of the same or different bacteria species, particularly if used prior to other investigation techniques that require more complex procedure. The advantages of the test, among the others, is quantification of the obtained results, whereas a principal drawback implicates the impossibility of detecting extracellular substance. The microscopy techniques have provided a direct insight in the structures formed by the investigated strains on the used substrates, with some limitations. They are related to the poor resolution features and two-dimensional image obtained by light microscopy, as well as deformation of three-dimensional biofilm structures in the preparation for scanning electron microskopy.