Xylitol production from wheat straw hemicellulosic hydrolysate: hydrolysate detoxification and carbon source used for inoculum preparation

Abstract

Wheat straw hemicellulosic hydrolysate was used for xylitol bioproduction. The use of a xylose-containing medium to grow the inoculum did not favor the production of xylitol in the hydrolysate, which was submitted to a previous detoxification treatment with 2.5% activated charcoal for optimized removal of inhibitory compounds.

Evaluation of hexose and pentose in pre-cultivation of Candida guilliermondii on the key enzymes for xylitol production in sugarcane hemicellulosic hydrolysate

“…Similar to this work, Kastner et al (2001) during synthetic medium fermentation showed a enhancement on xylose consumption and xylitol production by using C. tropicalis previously grown in xylose instead of glucose. In the other hand Canilha et al (2008) during the bioconversion of xylose-to-xylitol in wheat straw hemicellulosic hydrolysate by C. guillliermondii which was pregrown in a medium containing glucose (37 g l -1 ) as the sole carbon source verified that the bioconversion parameters were slightly better than those observed when both glucose (7 g l -1 ) and xylose (30 g l -1 ) were used as carbon sources in the medium used to grow the inoculum. According to these authors, the maximum xylitol production (30.5 g l -1 ) was achieved after 72 h of fermentation, resulting in productivity of 0.42 g l -1 h -1 and bioconversion yield of 0.59 g g -1 .…”

“…In this case, it was obtained the highest cell biomass (10.6 g l -1 ), which was 7.5 and 20.0% higher than inoculum previously grown in xylose and in a mixture of glucose and xylose, respectively. This behavior was not verified by Canilha et al (2008) using the same yeast pre-grown in a medium elaborated with xylose ? glucose or just glucose and cultivated in wheat straw hemicellulosic hydrolysate detoxified with 2.5% active charcoal once these authors found a higher biomass when a mixture of sugars was employed.…”

Xylitol production byCyberlindnera(Williopsis) saturnus, a tropical mangrove yeast from xylose and corn cob hydrolysate

“…Acid-hydrolysate-based medium from agroindustrial wastes has often been used for the production of platform chemicals and fuels due to its availability, as well as its economy especially in a tropical country like India (Prakasham et al 2009). C. guilliermondii when grown on wheat straw and rice straw resulted in differential xylitol yields of 0Á59 g g À1 (Canhila et al 2008) and 0Á72 g g À1 (Mussatto and Roberto 2004). C. tropicalis (Ling et al 2011) and D. hansenii (Prakash et al 2011) have also produced similar yields of 0Á73 g g À1 and 0Á69 g g À1 on corn cob and sugar cane bagasse hydrolysates, respectively.…”

Detoxification of Lignocellulosic Hydrolysates for Improved Bioethanol Production

“…The detoxification of hemicellulose hydrolysates, by activated charcoal is known to be a cost effective with high capacity to absorb compounds without affecting levels of sugar in hydrolysate [Canilha et al, 2008;Chandel et al, 2007a;Mussatto & Roberto, 2001]. The effectiveness of activated charcoal treatment depends on different process variables such as pH, contact time, temperature and the ratio of activated charcoal taken versus the liquid hydrolysate volume [Prakasham et al, 2009].…”