Repeated Batch Cell-Immobilized System for the Biotechnological Production of Xylitol as a Renewable Green Sweetener
- PDF / 325,483 Bytes
- 10 Pages / 439.37 x 666.142 pts Page_size
- 81 Downloads / 172 Views
Repeated Batch Cell-Immobilized System for the Biotechnological Production of Xylitol as a Renewable Green Sweetener Boutros Sarrouh & Silvio Silvério da Silva
Received: 10 December 2012 / Accepted: 30 January 2013 / Published online: 9 February 2013 # Springer Science+Business Media New York 2013
Abstract The present paper studies the biotechnological production of xylitol using sugarcane bagasse hydrolysate in a repeated batch fermentation system with immobilized cells of Candida guilliermondii FTI20037. Immobilized cell system is considered as an attractive alternative to reuse the well-grown and adapted yeast cells in a new fresh fermentation media, without the need of the inoculum stage. In this work, seven repeated batches were performed in a fluidized bed bioreactor using immobilized cells in calcium alginate beads. According to the obtained results it was observed that the immobilized cells of C. guilliermondii can be reused for six successive batches maintaining an average xylitol yield (Yp/s) of 0.7 g/L and a volumetric productivity (Qp) of 0.42 g/Lh at the end of 432 h of fermentation. On the other hand, in the seventh batch (504 h), a decrease of 44 % in the final concentration of xylitol was observed. This reduction can be explained by the possible diffusion and accumulation of insoluble substances, found in the hemicellulosic hydrolysate, in the interior of the immobilization support resulting in substrate mass transfer limitations. Keywords Xylitol . Immobilized cells . Repeated batch fermentation . Fluidized bed reactor . Lignocellulosic hydrolysate Analytical Nomenclature Final xylitol concentration (in gram xylitol per liter) Pf Initial xylitol concentration (in gram xylitol per liter) Pi Overall xylitol production rate (in gram xylitol per liter per hour) Qp Initial xylose concentration (in gram xylose per liter) So Final xylose concentration (in gram xylose per liter) Sf Immobilized cell concentration in the reactor (in gram cells per liter) XrI B. Sarrouh : S. S. da Silva Biotechnology Department, University of São Paulo/Lorena, Campinho Road s/n., P.O. Box: 12600–970, Lorena, São Paulo, Brazil B. Sarrouh (*) Institute of Biological Sciences, Federal University of Minas Gerais (UFMG-ICB), Belo Horizonte, Minas Gerais CEP 31270-901, Brazil e-mail: [email protected]
2102
Yp/s E t FBR CV
Appl Biochem Biotechnol (2013) 169:2101–2110
Xylitol yield based on xylose consumption (in gram xylitol per gram xylose) Conversion efficiency of xylose to xylitol (in percent) Fermentation time (in hour) Fluidized bed reactor The coefficient of variation is defined as the ratio of the standard deviation to the mean
Subscripts Starting value p Xylitol s Xylose X Biomass o
Introduction Xylitol is a five-carbon sugar alcohol, a polyol that has beneficial health properties. It prevents dental caries and acute otitis media (ear infection) in small children [1–3]. Xylitol has almost the same sweetness as sucrose, but with an energy value of only 2.4 cal/g compared to the 4 cal/g of sucrose. Xylitol has a negativ
Data Loading...
