Aspects of Microbial Biofilms in Water Treatment

Global water crisis created due to increasing population and its demands needs to ascertain proper water management practices. Biofilm, which is a conis the fundamental unit of atgregation of microbial cells that are irreversibly attached to the surface and confined within the matrix of polysaccharide material, plays a major role in water treatment and reuse technology. A biofilm structure has a specific architecture that consists of microbial cells and extracellular polymeric substance provided with an ideal environment for the exchange of genetic material between cells. The growth and attachment process depend on the growth medium, substratum, and the cell surface. Biofilms are the main component of membrane bioreactors. The microorganisms present in the biofilms participate actively in contaminant bioremediation and degrade the organic contaminants of the polluted water. The planktonic-biofilm transition is a highly regulated and complex process that depends on the phenotypic characteristics of the bacteria and environmental factors. The microorganisms that help in biofilm formation have specific regulatory genes and communicate through quorum sensing which in turn can initiate certain biofilm processes such as detachment. Recently, studies have identified the genes and regulatory circuits which are involved in initial cell surface interactions, biofilm maturation, detachment, and the conversion of biofilm microbial cells into planktonic mode of growth. This chapter explores the ways of formation and architecture of biofilms and deals with the ecology of the surface microbes, their growth control mechanisms, and their role in water reclamation system.