Sunday, April 29, 2007

Loofa sponge as biosupport for cell immobilization in xylitol bioproduction

Tais C. Coelho, Boutros F. Sarrouh, Diego T dos Santos, Juan D. Rivaldi, and Silvio S. Da Silva. Biotechnology, USP-LORENA, Rod. itajuba/Lorena km 74,5, Lorena-SP, Brazil

Currently discoveries about newsly applications of xylitol, a high-type sweetener, have been impelling the biotechnological researches around alternative technologies to its production. The uptake of xylose from hemicellulosic hydrolysates becomes more feasible by the use of repeated batch systems, due to the cell adapting to inhibitory compounds. Besides this aspect, the cell immobilization technique offers high cell loads in the medium, acting directly on the fermentative parameters. Loofa sponge, the matured and dried fruit from Luffa cylindrica is a high-porous fiber, with low cost and high mechanical strength. This biomaterial represents an important feedstock that can be used as cell immobilization in different bioprocesses. This work presents the improvement of xylitol production from xylose-rich-hydrolysate obtained from sugarcane bagasse, by Candida guilliermondii FTI20037 immobilized in milled steam treated loofa in repeated batch systems. The fermentation process was performed in 125 mL Erlenmeyer flasks, containing hemicellulosic hydrolysate and nutrients, under 200 rpm at 30°C during 5 batch cycles. According to the results, the repeated batch system improved 35,6% and 15,9% in the values of productivity and efficiency, respectively. Loofa sponge showed as a useful matrix that can be used efficiently in the xilitol bioproduction. ACKNOWLEDGEMENTS: FAPESP, CAPES