Temperature‐Sensitive Hydrogels: A Gentle Way of Concentrating Cellulase Enzymes

The swelling behaviour of a poly(N‐isopropylacrylamide) temperature sensitive hydrogel in fermentation broth was determined as a function of the temperature and compared with that in water. The feasibility of the gel as a device for concentration of cellulase enzymes, produced by the fermentation of the fungus Trichoderma reesei RUT C‐30, was also studied. For the same particle size, gels with different composition showed differences in the swelling time and in the extent of swelling. The time required for collapsing was independent of both the monomer concentration and the degree of crosslinking. During swelling, the gels absorb water and low molecular weight solutes (<100 g/mol), excluding macromolecules such as proteins (>10 kD). The enzymes were concentrated in the solution non‐ absorbed by the gels. Mass balances for fermented broth, total soluble protein and enzyme activity showed a good recovery.