Xylitol fermentation by Candida subtropicalis WF79 immobilized in polyacrylic hydrogel films

Abstract

Polyacrylate hydrogel films were used as immobilization matrices for cell entrapment of the yeast strain, Candida subtropicalis WF79, isolated from sugarcane bagasse. The hydrogel films with immobilized viable yeast cells were employed for the bioconversion from xylose to xylitol. The hydrogel was prepared from the monomers of 2-hydroxyethyl methacrylate (HEMA), methacrylic acid (MAA), and N,N-dimethyl acrylamide (DMA) with polyethylene glycol diacrylate (PEG-DA, weight-average molecular weight Mw=400 and 1,000 g/mol) as the crosslinking agent. The mechanical properties and fermentation yields of the immobilized polyacrylate hydrogel film with different monomeric formulation were investigated. Fermentation was carried out in a medium of 100 mL aqueous solution containing various amount of xylose. The conversion rate of xylose to xylitol conversion reached a maximum value of 80% after 120 h. The bioconversion activity gradually declined, after 720 h, to 65% conversion at 1,080 h.