Isolation, characterization and stress response of dental plaque forming bacteria

Abstract

The current work deals with the studies of isolation and characterization of oral biofilm forming bacteria. The major constituent of biofilm other than bacterial cells is the Extracellular Polymeric Slime matrix (EPS) which is secreted by the bacterial cells themselves. Physical properties of biofilms like attachment, mechanical strength, antibiotic resistance can be attributed to EPS matrix. In this study, attempts were made to study the stress response of bacteria isolated and their chemotactic response. Further attempts were made to characterize the EPS matrix by chemical as well as spectroscopic studies. The bacterial strains isolated were characterized to be Staphylococcus aureus, Staphylococcus salivarius, Streptococcus mitis, Streptococcus oralis, Bacillus subtilis by biochemical identification method. SEM micrographs taken confirmed the formation of biofilm. It was observed that cell attachment was maximum when glucose was used as the sole carbon source. Test for biofilm formation in presence of metal salts of Iron and Zinc showed moderate to high inhibition of film formation. The chemotaxis studies carried out in present work indicates the poor response of two strains towards fructose and sucrose. The EPS characterization result indicated the presence of a macromolecular complex constituting of carbohydrate, protein, lipids and nucleic acids.