Bacterial Cell-Mineral Interface, Its Impacts on Biofilm Formation and Bioremediation

Abstract

This chapter aims to provide a better understanding of the bacterial cell attachment and biofilm formation on the mineral surfaces, which would result in improving our knowledge about: the interfacial forces governing the bacterial cell attachment, predicting trends of the biofilm formation and consequently biodegradation rates, and the contaminant’s fate in the diverse geological media (Pouran HM. Studying molecular and nanoscale interactions at metal oxide surfaces and their effects on bacterial adhesion, 2009).

In both aqueous and terrestrial environments, bacterial cells tend to be attached to a surface and form biofilm. If they are associated to, e.g., a mineral surface, bacterial cells would remain in a more stable microenvironment instead of being removed by the water shear stress. Even the bacterial planktonic phase can be considered as a mechanism for translocation from one surface to the other rather than a prime lifestyle (Watnick and Kolter 2000; Young 2006). The biofilm formation, which completely covers the surface, initially begins by the adhesion of a small quantity of cells (Vadillo-rodri et al. 2006; Pouran et al. 2017).

Among the different indigenous microbial species in the contaminated environments, some are capable of degrading pollutants and participating in the environmental remediation process. The bioremediation process of the contaminated soils and waters is often considered a promising low risk management tool. Even when the contamination poses an imminent threat and other approaches are essential, bioremediation often is a viable secondary strategy for the site maintenance (Haws et al. 2006; Pouran et al. 2017).

Natural environments are dynamic and complex systems; therefore, characterization and identifying the underlying processes governing the contaminant’s fate are not easy. Examples of the natural environments heterogeneity are the diverse physicochemical properties of the soils and aquifers matrices (Stumm and Morgan 1996). As the soils and sediments are the prime surfaces for the bacterial cell attachment in most natural environments, elucidation of the surface properties of these constituents and their role in initiating cell adhesion and biofilm formation are of the key importance in understanding the bioremediation process. In fact, the cell-mineral interface reactions not only influence the biodegradation process but many natural phenomena are affected by them.

Understanding role of physicochemical interactions at the bacterial cells and minerals interface in the cell adhesion (as well as biofilm formation, development, and behavior) is essential for planning effective bioremediation techniques. It could potentially help us to predict the contaminants’ fate, and trends of the biodegradation rates in different environments. Consequently, the improved knowledge of the cell-mineral interface enable us to design and apply more sophisticated bioremediation techniques as a viable approach towards tackling the soil and water environmental pollution problems. Figure 1 schematically represents an aquifer and biofilm formation on some of the most abundant minerals in the environment, iron and aluminum oxides. It also indicates some the major effects of cell-mineral interface interactions on different environmental processes (Stumm and Morgan 1996; Zachara and Fredrickson 2004; Cornell and Schwertmann 2003).