Adaptation and reutilization ofCandida guilliermondii cells for xylitol production in bagasse hydrolysate

Inhibitory effect of acetic acid on bioconversion of xylose in xylitol by Candida guilliermondii in sugarcane bagasse hydrolysate

“…Xylose, glucose, arabinose, xylitol and acetic acid were determined by HPLC Shimadzu (Kyoto, Japan) provided with a refractive index (RI) detector and Bio Rad (Hercules, CA) Aminex HPX-87H column (300x7.8mm) at 45ºC, using 0.01N H2SO4, a flow rate of 0.6mL.min -1 , and a sample injector volume of 20mL. Furfural and hydroxymethylfurfural concentrations were also determined by HPLC Shimadzu provided with a dual l absorbance detector (SPD-10 A uv-vis) at 276nm wavelength and a Hewlett-Packard RP 18 (200 mm) column at 25ºC, using a 1:8 acetonitrile:water ratio, 1% acetic acid as the eluent, a flow rate of 0.8mL.min -1 and a sample volume of 20mL (17). Total phenols concentration was determined by spectrophotometry (Beckman DU 640B spectrophotometer) as described by KIM and YOO (7), using phenol as the standard compound.…”

“…T12 T24 T48 T54 T12 T24 T48 Reductions of 37.10% and 52.17% in xylitol yield and productivity respectively occurred when acetic acid was added to the medium after 12h, confirming that the negative effect of the acetic acid is associated with the fermentation time when this acid was added to the medium. These results agree with those previously found for the same yeast strain using synthetic medium (4) or hydrolysates from eucalyptus (3) and sugarcane bagasse (15,17).…”

Use of Immobilized Candida Cells on Xylitol Production from Sugarcane Bagasse

“…In this area, after the colonization, the cells begin to exhibit a stronger metabolic activity, with a consequent increase in the fermentative param eters (Omar, 1993;Dominguez, 1998). On the other hand, recycling and adaptation of the cells to the hydrolysate result in better ferm en tative parameters, possibly due to the adaptation of the cells to the toxic compounds generated dur ing the acid hydrolysis of lignocellulosics which in terfere with cell growth and xylitol production rates (Sene et al, 1998).…”

“…The adaptation of the microorganism to the hy drolysate (Chen and Gong, 1985;Felipe et al, 1996b;Sene et al, 1998), the recycle of cells (Sene et al, 1998) and the use of high cell concentrations (Chung and Lee, 1985;Felipe et al, 1996a;Felipe et al, 1997a) are procedures for reducing the toxic effects of the hydrolysate on the activity of the microorganisms and for improving the fermen tative param eters of xylitol production. Ferm enta tions in repeated batch mode are appropriate for this bioprocess because they prom ote a good adaptation of the cells to the hydrolysate.…”

Improvement of biotechnological xylitol production by glucose during cultive of Candida guilliermondii in sugarcane bagasse hydrolysate

“…2) could be directly associated with xylitol consumption by yeast. This reduction in xylitol concentration was also observed during the cultivation of C. guilliermondii in synthetic medium (Felipe et al 1995) and in sugarcane bagasse hydrolysate Sene et al 1998), and also during the cultivation of C. tropicalis in synthetic medium (Walther et al 2001). Recently, experiments performed in our laboratories revealed that xylitol was utilized as a carbon source by C. guilliermondii for cell growth (Silva and Felipe 2006).…”