Proceedings Volume 2010 (format .pdf) - SimpBTH

STUDIES ON IMMOBILIZATION OF CELLULASES BY SORPTION ANDENTRAPMENT ON SOLID SUBSTRATES AND PERMSELECTIVEMEMBRANESDIANA GROPOSILA-CONSTANTINESCU 1) , IRINA LUPESCU 2) , LUMINITAVISAN 1) , MISU MOSCOVICI 2) , RADU TOMA 1)1) University of Agronomical Sciences and Veterinary Medicine of Bucharest, Faculty of Biotechnology2) National Institute for Chemical-Pharmaceutical Research & DevelopmentABSTRACTCellulases, due to their capacity to depolymerise cellulose into fermentable sugars areessential components in the production of bioethanol from lignocellulosic materials. Developing ofnew and efficient techniques of immobilization leads to superior biocatalysts with increasedperformances.Immobilization experiments were performed using a commercial cellulase complex andAmberlite polymeric resins XAD-7, XAD-8, chitosan and glutaraldehyde. Determination ofcellulolytic activity and protein content were performed spectrofotometrically.Immobilization yields of 90 percent were obtained when the ionic strength of the enzymaticsolution was of 10-25 mM and the concentration of cellulases in the solution was 5%, correspondingto 0.2 g of enzyme per g of adsorbent. Maximum irreversible immobilization yield by reticulation ofthe enzyme with glutaraldehyde was 75 percent and was obtained using a glutaraldehyde/proteinratio of 2.5/1. In case of chitosan entrapment, experiments showed that the maximum immobilizationyield of 60 percent was obtained at 1/0.053 chitosan/glutardehyde ratio and 12.5/1 chitosan/proteinratio.INTRODUCTIONCellulases, due to their capacity to depolymerise cellulose into fermentablesugars are essential components for the production of bioethanol fromlignocellulosic materials. Developing of new and efficient techniques ofimmobilization leads to superior biocatalysts with increased performances.ObjectivesThe presented study had two main objectives: first the immobilization ofcellulases by adsorption on solid substrates combined with reticulation and second,the immobilization of cellulases by entrapment in natural polymer matrices.MATERIALS AND METHODSExperiments were performed using a commercial cellulase complex andAmberlite polymeric resins XAD-7, XAD-8, chitosan and glutaraldehyde asimmobilization supports.Determination of cellulolytic activity and protein content were performedspectrofotometrically (λ=540 nm).213