Optical and Electron Microscopic Study of the Morphology and Ultrastructure of Biofilms Formed by Streptococcus pyogenes

Abstract

Our study confirmed the capacity of S. pyogenes strains to form biofilms on abiotic surfaces. Chains of streptococci surrounded by bluish film were seen under a microscope after alcian blue staining of the preparations grown on slides. On ultrathin sections in transmission electron microscope, the extracellular matrix (indicator of biofilm maturity) became visible after staining with alcian blue. Microscopy of the sections shows structures characteristic of a biofilm in spaces between the cells. Scanning electron microscopy also demonstrates the presence of a biomembrane. Importantly that type 1M strain forming in fact no membranes when cultured on plastic plates (Costar) formed biofilms on the glass. It seems that the conditions for the biofilm formation on the plastic and on the glass differ, due to which the exopolymeric matrices formed on different surfaces vary by biochemical composition.