Several cell disruption methods were tested on Nannochloropsis gaditana, to evaluate their efficiency in terms of cell disintegration, energy input and release of soluble proteins. High-pressure homogenization (HPH) and bead milling were the most efficient with >95% cell disintegration, ±50% (w/w) release of total proteins and low energy input (<0.5kWh.kg). Enzymatic treatment required low energy input (<0.34kWh.kg), but it only released ±35% protein (w/w). Pulsed Electric Field (PEF) was neither energy-efficient (10.44kWh.kg) nor successful for protein release (only 10% proteins w/w) and cell disintegration. The release of proteins after applying HPH and bead milling always required less intensive operating conditions for cell disruption. The energy cost per unit of released protein ranged from 0.15-0.25 €.kg in case of HPH, and up to 2-20 €.kg in case of PEF.

Thermal deactivation of free and immobilized /3-glucosidase from Penicillium funiculosum has been studied in the temperature range 30-70 "C. Immobilization results in a remarkable increase in /%glucosidase thermal stability. A two-step series deactivation mechanism has been used to describe the experimental results for both free and immobilized B-glucosidases. The kinetic equations resulting from this model fit our experimental results with a mean deviation of less than 10%.

Cellulase from four different fungi and B-glucosidase from almonds were immobilized on the inner surface of nylon tubing. The highest values of P-glucosidase activity retention on the support were obtained when P. friniculosurn and N. crassa were used as the enzyme source. A comparative study of the thermal stability referring to B-glucosidase activity was developed using free and immobilized enzymes. The most stable fi-glucosidases (from P. funiculosum and A. niger) did not show an appreciable change in its thermal stability after immobilization. An important increase in thermal stability was observed when less stable P-glucosidases (from T. reesei, N. crassa and almonds) were immobilized.

The kinetics of cellobiose hydrolysis was studied using Pglucosidase from Prnicilliumfuniculosum, both free and immobilized on nylon powder, at different temperatures, pH values, enzymatic activities and initial cellobiose and glucose concentrations. The experimental results were fitted to a kinetic model by considering the substrate and product inhibitions as well as the thermal deactivation of Pglucosidase with a mean deviation of less than 10%. The immobilization of Pglucosidase led to an increase in the stability of the enzyme against changes in the pH value.

Pretreated wheat straw was enzymatically hydrolyzed in 250-ml flasks using the culture filtrate of Trichoderrna reesei QM-9414. The influence of the initial enzymatic activity in the liquid phase was studied. The unreacted core model was used to analyze the experimental data obtained at 40, 46 and 50 "C. The model adequately describes the data for hydrolysis times lower than 10 h.