Xylitol Production from Sugarcane Bagasse Hydrolyzate in Fluidized Bed Reactor. Effect of Air Flowrate
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- 作者：J. C. Santos ; W. Carvalho ; S. S. Silva ; and A. Converti
- 刊名：Biotechnology Progress
- 出版年：2003
- 出版时间：August 2003
- 年：2003
- 卷：19
- 期：4
- 页码：1210 - 1215
- 全文大小：93K
- 年卷期：v.19,no.4(August 2003)
- ISSN：1520-6033
文摘
Cells of Candida guilliermondii immobilized onto porous glass spheres were culturedbatchwise in a fluidized bed bioreactor for xylitol production from sugarcane bagassehemicellulose hydrolyzate. An aeration rate of only 25 mL/min ensured minimum yieldsof xylose consumption (0.60) and biomass production (0.14 gDM/gXyl), as well asmaximum xylitol yield (0.54 gXyt/gXyl) and ratio of immobilized to total cells (0.83).These results suggest that cell metabolism, although slow because of oxygen limitation,was mainly addressed to xylitol production. A progressive increase in the aerationrate up to 140 mL/min accelerated both xylose consumption (from 0.36 to 0.78 gXyl/L·h) and xylitol formation (from 0.19 to 0.28 gXyt/L·h) but caused the fraction ofimmobilized to total cells and the xylitol yield to decrease up to 0.22 and 0.36 gXyt/gXyl,respectively. The highest xylitol concentration (17.0 gXyt/L) was obtained at 70 mL/min, but the specific xylitol productivity and the xylitol yield were 43% and 22% lowerthan the corresponding values obtained at the lowest air flowrate, respectively. Theconcentrations of consumed substrates and formed products were used in materialbalances to evaluate the xylose fractions consumed by C. guilliermondii for xylitolproduction, complete oxidation through the hexose monophosphate shunt, and cellgrowth. The experimental data collected at variable oxygen level allowed estimatinga P/O ratio of 1.35 molATP/molO and overall ATP requirements for biomass growthand maintenance of 3.4 molATP/C-molDM.