Influence of the toxic compounds present in brewer's spent grain hemicellulosic hydrolysate on xylose-to-xylitol bioconversion by Candida guilliermondii

Solange I. Mussatto, Giuliano Dragone, Inês Conceicao Roberto

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Fermentation media containing different concentrations of toxic compounds were prepared from brewer's spent grain (BSG) hemicellulosic hydrolysate, and used for xylose-to-xylitol bioconversion by Candida guilliermondii. Such fermentation media were composed of the hydrolysate in the following ways: raw (RH); concentrated four-fold (CH); concentrated and treated with activated charcoal (TCH); raw supplemented with sugars until a concentration four-fold higher (SRH); concentrated and subsequently diluted but supplemented with sugars until a concentration four-fold higher (SDCH). All media presented an initial xylose concentration of 85 g/l, except RH, which contained 23 g/l xylose. Fermentation results revealed that the sugars supplementation to raw hydrolysate favored the xylitol production. Nevertheless, xylitol production from CH was negatively affected due to the high concentration of toxic compounds present in the medium. The hydrolysate treatment with activated charcoal partially removed the toxic compounds, and the xylitol production was higher than in CH, but not so efficient as in SRH. It was thus concluded that to obtain an efficient xylose-to-xylitol bioconversion from BSG hydrolysate, the sugars concentration must be increased, but the toxic compounds concentration must be reduced to the same level present in the raw hydrolysate.
Original languageEnglish
JournalProcess Biochemistry
Volume40
Issue number12
Pages (from-to)3801-3806
ISSN1359-5113
DOIs
Publication statusPublished - 2005
Externally publishedYes

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