Enhancing cellulase foam fractionation with addition of surfactant.

Foam fractionation cannot be used to recover cellulase from an aerated water solution effectively because cellulase by itself can produce only a small amount of foam. The addition of a surfactant can, however, increase the foamate volume and enhance the concentration of cellulase. We studied three detergents individually added to a 200 mg/L cellulase solution to promote foaming. These detergents were anionic, cationic, and nonionic surfactants, respectively. Although contributing to foam production, it was observed that nonionic surfactant (Pluronic F-68) barely concentrated cellulase, leaving the enrichment ratio unchanged, near 1. With anionic surfactant, sodium dedecyl sulfate, and cationic surfactant, cetyltrimethylammonium bromide (CTAB), the enrichment ratio became much larger, but cellulase denaturation occurred, reducing the activity of the enzyme. When CTAB was used to help foam cellulase, beta-cyclodextrin was subsequently added to the foamate to help restore the enzyme activity.