Mechanism of biofilm formation and host interactions.

The prevalence of antimicrobial resistance in most of the microbial species, majority of human microbial infections and diseases occur due to the formation of biofilms in Gram- positive and Gram-negative bacteria. The species of bacteria include Pseudomonas aeruginosa, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Streptococcus viridans, Staphylococcus aureus, Enterococcus faecalis etc. Not only bacteria but there exists some fungi and protists that may also form biofilms is the factors are favourable. The biofilms are constituted as 10 % microbial mass and 90 % water. 50-90 % of the biofilm matrix is composed of polysaccharides as the organic component. The biofilm makes a microbial species pathogenic in nature. The mechanism of biofilm formation involves the process of quorum sensing. It is a cell-to-cell communication process that controls the regulation of gene expression for the biosynthesis of molecules required for bacterial biofilms. Depending upon the type and the genes present, the mechanism of quorum sensing differs between species to species. In this chapter, different mechanisms involved in biofilm formation in species will be discussed in detail and their specific interactions with the host organisms.