Enhanced Xylitol Production by Precultivation of Candida guilliermondii Cells in Sugarcane Bagasse Hemicellulosic Hydrolysate |
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Authors: | Rita CLB Rodrigues Luciane Sene Gilvane S Matos Inês C Roberto Adalberto Pessoa Jr Maria GA Felipe |
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Institution: | Departamento de Biotecnologia, DEBIQ, Faculdade de Engenharia Química de Lorena, FAENQUIL, Lorena, SP, Brazil. rita@debiq.faenquil.br |
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Abstract: | The present work evaluated the key enzymes involved in xylitol production (xylose reductase XR] and xylitol dehydrogenase
XDH]) and their correlation with xylose, arabinose, and acetic acid assimilation during cultivation of Candida guilliermondii FTI 20037 cells in sugarcane bagasse hemicellulosic hydrolysate. For this purpose, inocula previously grown either in sugarcane
bagasse hemicellulosic hydrolysate (SBHH) or in semidefined medium (xylose as a substrate) were used. The highest xylose/acetic
acid consumption ratio (1.78) and the lowest arabinose consumption (13%) were attained in the fermentation using inoculum
previously grown in semidefined medium (without acetic acid and arabinose). In this case, the highest values of XR (1.37 U
mg prot−1) and XDH (0.91 U mg prot−1) activities were observed. The highest xylitol yield (∼0.55 g g−1) and byproducts (ethanol and glycerol) formation were not influenced by inoculum procedure. However, the cell previously
grown in the hydrolysate was effective in enhancing xylitol production by keeping the XR enzyme activity at high levels (around
0.99 U·mgprot−1), reducing the XDH activity (34.0%) and increasing xylitol volumetric productivity (26.5%) with respect to the inoculum cultivated
in semidefined medium. Therefore, inoculum adaptation to SBHH was shown to be an important strategy to improve xylitol productivity. |
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