Biofilm-mediated bioremediation of pollutants from the environment for sustainable development

Abstract Microbial biofilm formation is a primary step of bioremediation for any hazardous environmental pollutants. Biofilms are group of microbes in which the cells are attached irreversibly to a solid surface and deep-seated in a matrix which is made up of extracellular polymeric substances (EPSs). Cellular biochemistry and social interactions between microbial cells facilitate the exchange of genetic material, metabolites, and signal molecules between cell to cells, sorption, and the ability to immobilize pollutants. The absorption, adsorption, and immobilization of materials occur via ion exchange, complexation, and precipitation. Chemotactic responses of microorganisms also regulate the swim towards complex pollutants followed by biofilm formation, increase pollutant bioavailability by surfactant production and cometabolizing the pollutants leads to degradation or transformation. Intracellular and extracellular enzymes of biofilm degrade polyaromatic hydrocarbons (PAHs) by the addition of an oxygen atom on the benzene ring which opens the aromatic ring. The dehydrogenase or oxidoreductase produces intermediates of the tricarboxylic acid cycle and leads to the metabolization of PAHs. The main steps in the biofilm formations are attachment, aggregation, maturation, and dispersal. The major quorum sensing (QS) signaling of Gram-negative bacteria and Gram-positive bacteria is N-acyl homoserine lactone (AHL) and autoinducing peptide (AIP), respectively. Simultaneously, some metabolic products also act as quorum quenching molecules that make the bioremediation process complex and challenging.