Encapsulation of Bacteria for Biodegradation of Gasoline Hydrocarbons

Gasoline hydrocarbons are a common source of contamination to soil and aquifer systems. Biodegradation of these contaminants by hydrogel-encapsulated bacteria is a novel technique for bioremediation of contaminated sites. Hydrogel capsules provide a stable, consistent, and protective microenvironment for prolonged survival and metabolic activity of encapsulated cells. This monograph presents the materials and methods for encapsulation of gasoline-degrading bacteria in gellan gum microspheres. The microencapsulation process is based on a two-phase dispersion technique, termed emulsification-internal gelation. The sphere formation process involves the dispersion of two immiscible liquid phases resulting in a water-in-oil (w/o) emulsion. A suspension of viable cells in an aqueous solution of gellan gum (disperse phase) is emulsified in a hydrophobic phase such as canola oil (continuous phase). The gelation of the small droplets of the dispersed phase is subsequently initiated by decreasing the emulsion temperature. Changing the emulsion conditions can alter the size distribution of microspheres. The emulsification-internal gelation method is applicable to encapsulation of other microbial degraders in macro- or microspheres subject to the employment of proper emulsion conditions.