A method for encapsulation of viable and metabolically active microorganisms in polyurethane foam

Polyurethane foam has several advantages over the hydrogels, alginate, carageenan and acrylamide, as an entrapment agent for live bacteria. These advantages include: 1) inert structure, 2) foam structure does not require ions for stability, 3) foam is semi-rigid and flexible, 4) the foam has better mechanical strength. The major disadvantage of polyurethane foam is toluene present in the foam hardening agent which results in low bacteria viability during encapsulation. In this study a procedure was developed to encapsulate Pseudomonas putida Idaho and Burkholderia cepacia G4 into polyurethane foam while maintaining cell viability.

A standard method for growth of each bacteria and encapsulation into the foam was developed. Experimental variables tested were, 1) formulation of the foam prepolymer, 2) use of protective agents during encapsulation, 3) bacterial growth medium and 4) temperature of the encapsulation. Bacteria viability was determined by performing plate counts (CFU) and comparing total counts of encapsulated vs. unencapsulated cells. Viability was also quantified by measuring encapsulated cell metabolic activity.