Possibilities for recycling cellulases after use in cotton Processing. Part I : effects of end-product inhibition, thermal and mechanical deactivation and cellulase depletion by adsorption

摘要

Preliminary recycling experiments with cellulase enzymes after cottontreatments at 50°C showed that activity remaining in the treatment liquorswas reduced by about 80% after five recycling steps. The potential problemsof end-product inhibition, thermal and mechanical deactivation, and theloss of some components of the cellulase complex by preferential and orirreversible adsorption to cotton substrates were studied. End-product inhibitionstudies showed that the build-up of cellobiose and glucose would beexpected to cause no more than 40% activity loss after five textile treatmentcycles. Thermal and mechanical treatments of cellulases suggested that theenzymes start to be deactivated at 60°C and agitation levels similar to thoseused in textile processing did not cause significant enzyme deactivation.Analysis of cellulase solutions, by fast protein liquid chromatography, beforeand after adsorption on cotton fabrics, suggested that the cellobiohydrolaseII (Cel6A) content of the cellulase complex was reduced, relative to the othercomponents, by preferential adsorption. This would lead to a markedreduction in activity after several treatment cycles and top-up with purecellobiohydrolase II would be necessary unless this component is easilyrecoverable from the treated fabric.