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In this study, laccase enzyme (L) from Agaricus bisporus was immobilized by entrapment into polyacrylamide (PAAm) and semi-interpenetrating polymer networks (semi-IPNs) prepared with either polyacrylamide/κ-carragennan (0.05g) [PAAm/ κ-car (0.05)] or polyacrylamide/κ-carragennan (0.1 g) [PAAm/ κ-car (0.1)]. The optimum pH was 6.0 for free L, 8.0 for PAAm-L, 8.5 for PAAm/κ-car (0.05)-L, and 9.0 for PAAm/κ-car (0.1)-L. The optimum temperature was determined as 45°C for free L and 60°C for all immobilized laccases. After 27 days of storage at 4°C, free enzyme lost its initial activity whereas immobilized enzymes retained 56 % (-)80% of their initial activities. The immobilized samples were used repeatedly 35 times by retaining 28 %-58 % of their initial activity. K(m(app)) values were calculated as 0.088, 0.139, 0.133, and 0.131 mM and Vmax values were found to be 2.83 x 10(-3), 4.51×10(-3), 4.76×10(-3), and 4.97×10(-3) mM min(-1) for free L and PAAm-L, PAAm/κ-car (0.05)-L, and PAAm/κ-car (0.1)-L, respectively.

In this work, modified carboxymethylcellulose (CMC) was used as a new support material for production of ethanol. Crosslinked graft copolymers of CMC with N-vinyl-2-pyrrolidone (N-VP) were prepared in different grafting yields. The beads material was characterized by means of fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and swelling experiment. Saccharomyces cerevisiae was immobilized using entrapment method in the graft copolymers of carboxymethylcellulose-g-poly(N-vinyl-2-pyrrolidone) (CMC-g-PVP) for ethanol fermentation. The effects of grafting yield, initial glucose concentration and crosslinker concentration on the yield of ethanol process were investigated. Reusability of the immobilized yeasts was investigated and found that the materials can be used four times without losing their activity. Ethanol production increased to 59.3 g/L from 46.4 g/L when percentage of N-VP in the graft copolymer was increased. The highest ethanol productivity was found to be 1.75-2.25 g/L h. Fermentation time decreased with the decreasing of crosslinker concentration. The results suggest that the proposed method for immobilization of Saccharomyces cerevisiae has potential in industrial applications for ethanol process.